[DA IMP]

Hello everyone.

I'm making a new build, almost from scratch, and was beginning to wonder if I should seriously consider a different HDD as my main disk.

This is my current main disk for the build (bought a while already):
Western Digital WD2500KS-00MJB0. 250GBs. SATA 3.0Gb/s (Is this the same as 300MB/s? Doesn't make much sense to me). 7200RPM. 16MBs buffer. Average seek: 8.9ms.

What I'm trying to find out, is the fastest options available in the market, for HDD speed.

My reasoning is...since I'm trying to make a really fast computer...shouldn't I give the HDD some serious consideration? It's the slowest device in the whole computer (ignoring the optic, obviously)...thus, any increase of speed in that area, will translate itself fully into the overall speed of the computer...am I right?

I know the main speed factor is transfer (ATA, SATA 1.5 and 3.0, etc.). What else factors in decisively?
Buffer barely matters if I already have 16MBs. By definition, the buffer will never add more than a slight bit of speed, unless it's hundreds of times bigger.

Is it the RPM? Should I seek SCSI drives then, with 10 or 15k RPM? I don't know their transfer speed really, how fast can these be?

If SATA has better transfer speed (it's newer technology after all, right?), should I seek a SATA with more RPM? Just how much faster does 10-15k RPM get me?

All these considered...what is the fastest I can get?

Thank you all for your time and help.

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Hard Disk Drives

Click on that link if you want to read in depth info for HDD's. 15000 RPM would be the highest you can go, but you would have to spend like $500 for 300GB, and you would have to spend extra money on a MOBO that can handle the interface (SAS), along with being able to keep it properly cooled. With all of that considered, I don't think that would be close in any to being worth it.

10000 RPM might be more worthwhile if you really want to pay the extra money for a decent speed boost. 300 GB Velociraptor is pretty much the only choice right now, but it is rated pretty good.

[Granz00]

Hard Disk Drives

Click on that link if you want to read in depth info for HDD's. 15000 RPM would be the highest you can go, but you would have to spend like $500 for 300GB, and you would have to spend extra money on a MOBO that can handle the interface (SAS), along with being able to keep it properly cooled. With all of that considered, I don't think that would be close in any to being worth it.

10000 RPM might be more worthwhile if you really want to pay the extra money for a decent speed boost. 300 GB Velociraptor is pretty much the only choice right now, but it is rated pretty good.

[DA IMP]

Mmmh, ok.

Let's see then...SCSI is out of the question then? I think you're suggesting SATA drives only...I guess that means SCSI is too slow in transfer speeds, despite being faster on RPM? And of course I'd want both speeds to be high...

Mmmmh...upon reading the wikipedia entry (and to think I tried there before...but checked "SCSI" not "hard drive')... I guess SAS (Serial SCSI) is the latest thing, an improvement upon SCSI, in the same way that SATA is an improvement upon PATA?

But these are just transfer interfaces, they don't really have anything to do with RPM, right? Both add to speed, but they're not truly related, I assume.

Some motherboards, even new models, don't handle SAS? Good to know.

I'm not seeing any info on this particular, on the motherboard I bought for the new build. It's this one: http://www.tigerdire...p?EdpNo=3581158

It's an ECS GeForce 6100PM-M2 v2.0. Socket AM2+. NVIDIA GeForce 6100/nForce 430 chipset.

From what I read on the wikipedia on SAS, it's current speeds are 3Gb/s...same as SATA 3.0 (sometimes called SATA2). That considered, how exactly is SAS that much better, right now? Its alleged future 6.0 will surely need some hardware update, with extra cost...

Back to RPM...
Can I expect a proportional change in speed, with RPM? That is, a 10k RPM HDD working 28% faster than a 7200RPM one? Roughly speaking...

I honestly don't need a very large disk for this. I already have the 250GBs SATA 3.0 for large storage (more than enough for my needs). Something much smaller would suffice as main disk. I've used a 40GBs disk as the main booting, working drive, up until now. Anything like that or a bit bigger, I'll be happy with. I'm prioritising speed in this one case.

[Neil Jones]

SATA II aka SATA 3Gb/s are theoretical maximums. Under most situations the speed difference between SATA I (1.5Gbps) are SATA II are hardly noticeable, all other things being equal.

RPM wise, just as you can notice the difference between a 5400rpm drive and a 7200rpm drive, you will notice it between 7200pm and 10,000rpm.

In theory SAS SCSI would be faster than SATA II however in practice it probably won't be until we get so far down the solid state drive route to a point where they don't wear out after a few thousand uses and that they're faster than mechanical driven drives - at the moment the gap is closing.

[DA IMP]

Neil Jones:

So, you're saying that, with something like the 250GBs drive I already have (SATA 3.0, 7200RPM, 16MBs buffer), I shouldn't bother with anything else, 'cos the difference in speed would be negligible?

I...really haven't stopped to notice the difference between different RPMs. The two disks I have right now are all too different, not just in the RPM. Comparing them with benchmarks or something, would throw a difference a lot bigger than what the RPM represents, 'cos the older one's an U-ATA100 on 4500RPM and a tiny 128k buffer...
Plus I'm sure after these many years of heavy usage, it's starting to lose some strength...it still works just fine, but it's not brand new.
AND until I upgrade to my new build, the 250GBs will keep working as SATA 1.5.

I'd need hard disks that are all the same, except for RPM pretty much, to do a good compare...

Theoretically then, the RPM difference with another SATA 3.0, that's 10-15k RPM, is negligible too? 'cos honestly, if it's something like 10%, I'm interested. It would translate entirely to the overall performance.

[Granz00]

I believe he was saying that there is a noticable difference between the 7200 RPM, and the 10000 RPM. So this means it would be worthwhile to upgrade, if you want to spend the extra money.

For the 15000 RPM, SAS type HDD's, it looks like you might have to spend around $800+ to get started with using these, and I have not seen a MOBO that supports SAS. You could afford to build another computer for what you would have to invest in this.

[shard92]

another thing is how you use the system... if all you do is surf the internet you probably won't notice as much of a difference either.... and personally I'd have dropped a little more money on a better motherboard... Not a fan of ECS.... Use to like them but they seemed to take a turn for the worse a few years ago... personally I like MSI particularly for AMD processors.... I also like Gigabyte and Asus if you research the model first ( they've had a few lemons lately... )

[Neil Jones]

So, you're saying that, with something like the 250GBs drive I already have (SATA 3.0, 7200RPM, 16MBs buffer), I shouldn't bother with anything else, 'cos the difference in speed would be negligible?

All other things being equal, the difference between 7200rpm and 10k rpm would be noticeable because the disk spins faster. Likewise, 10k to 15k is half as much again therefore it's noticeable.

I...really haven't stopped to notice the difference between different RPMs. The two disks I have right now are all too different, not just in the RPM. Comparing them with benchmarks or something, would throw a difference a lot bigger than what the RPM represents, 'cos the older one's an U-ATA100 on 4500RPM and a tiny 128k buffer...

Cache makes a big difference as its far faster than the rest of a drive as a whole. Bigger the cache, more stuff gets stored in it and if Windows can get something out the drive's cache it'll do so, speeding things up.

Plus I'm sure after these many years of heavy usage, it's starting to lose some strength...it still works just fine, but it's not brand new.
AND until I upgrade to my new build, the 250GBs will keep working as SATA 1.5.

Hard drives are mechanical instruments, eventually they'll wear out. Comparable to the brake pads on your car, they'll wear out as well.

As previously stated, SATA speeds are theoretical. You'll be hard pushed to spot the difference between SATA 1.5Gbps and SATA 3Gbps.

[DA IMP]

Ok...

Then, speed-wise, as long as we're talking SATA, it's better to focus on RPM, than whether it's SATA 1.5 or 3? A buffer is, by size and definition, a minor factor. Difference between 128k and 16MBs is important, but...between 8MB and 16MBs, I doubt it matters more than 3-5%, if that much.
I mean, I've read in a bunch of places, that buffer is severely overrated. And it does fit with my own experience. 16MBs and even 32MBs (the biggest I've seen so far), is negligible when compared to how much the HDD's full size and the files it can get to handle.

I cannot find anything that's both SATA 3 and above 7200 RPM...that's not also impossibly expensive for me.

So, how about this? http://techreport.com/articles.x/6390

It's only 74/80GBs, but that's enough for me as long as I have the 250GBs for storage and backups. It's SATA 1.5, but it's also 10k RPM and it has some really good seek times, it seems.
The 250GBs one has a an average seek of 8.9ms, while this one makes it 4.5. 8MBs buffer, too.

So, if SATA 1.5 is actually a small difference with SATA 3, I'd rather get this one for main HDD. And I'd spend around U$S60 on it. I think I cannot get a SATA 3 with 10k, for less than U$S150, if that cheap (I stopped looking for those when I saw the prices).

I'm aiming for speed...with a realistic budget, that is. XP will be the main OS in this build, and I'm tired of how its inefficient swap system eats away at everything, especially as the months/years pass since your last clean install.

This is going on a dual-core with 2GBs of DDR2-800. And the slowest is always gonna be the HDD regardless of build, so if I can speed it up by 20% or so, I'll gladly do so.

shard92: I've installed ECS boards in a bunch of systems, without any problems. MSI is also a good brand, agreed. I just got the ECS for an excellent price, and it has all I need, so I'll stick with it. I know Asus is supposed to be all better and stuff, but in my experience, ECS works just fine, and those others have nothing that justifies spending the big (for me) difference. The standards (chipset, slotss, connectors, support) are all the same in the end.

[DA IMP]

Ok, summing it up now: Apparently SCSI and SATA 1.5 are about same speed, transfer-wise? So, should I go for a SATA 1.5 with 10k RPM? Or actually try a SCSI with 15k RPM? Which one would be actually faster?

[stettybet0]

Sorry to sort of "start over" the discussion here, but some things need to be clarified.

There are three main things to consider when choosing a hard drive:

1. Interface (SATA, ATA, SCSI, etc.)
2. Rotational Speed (7200rpm, 10000rpm, etc.)
3. Aerial Density (The amount of storage being fit onto each hard drive platter. Ex. 250GB per platter, 320GB per platter, etc.)

Let's start with interface:

SCSI hard drives are meant for servers. In order to use them, you need an SCSI controller card, which can cost hundreds of dollars. The key difference between SCSI and SATA (besides the interface, of course) is that the SCSI controller has a separate processor built into it. This takes the load off your CPU and is specifically designed to access data on the hard drive in an optimal manner. However, as SATA drives now have the ability to use NCQ, the performance difference is typically negligible between single SCSI and SATA hard drives of the same speed. You will only see the real power of SCSI on a large RAID configuration (which are common in servers), since the SCSI processor will take care of RAID-related tasks rather than your CPU.

As for SATA:

SATA 1 (aka SATA 1.5 Gbit/s) hard drives communicate with the CPU at a rate of 1.5 Gbits per second. However, they only have the bandwidth to transfer 150MB/s. Likewise, SATA 2 (aka SATA 3.0 Gbit/s) hard drives communicate with the CPU at a rate of 3.0 Gbits per second. Similarly, they only have the bandwidth to transfer 300MB/s. It is important to keep in mind that the fastest SATA hard drive can only physically transfer data at 118MB/s, so neither limit has yet been reached. SATA 2 was developed preemptively to avoid the eventual bandwidth limitation of SATA 1. The conclusion here is that, assuming everything else is the same, there would be no difference between a SATA 1 and SATA 2 drive.

Rotational Speed:

The faster the hard drive spins, the faster it can access its data. So naturally, a hard drive that spins at 10000rpm will be able to access its data faster than a hard drive that spins at 7200rpm. But accessing the data is only half the battle, which leads us to...

Aerial density:

As previously mentioned, aerial density is the amount of storage has been squeezed onto each platter in the hard drive. The more storage is on the platter, the closer together each piece of data is, which means the hard drive head reading the data has to move a shorter distance to get to the next piece of data. This translates to faster transfer speeds. So while some 10000rpm hard drives (such as the 74GB Raptor you mentioned) may have faster access times, 7200rpm hard drives with high aerial densities such as this 640GB WD hard drive will have faster transfer times and better overall performance.

So, the bottom line is:

The VelociRaptor is the best overall desktop performer due to is high rotational speed and decent aerial density. However, it is certainly not the most economical option. The 640GB WD hard drive that I previously mentioned will perform similarly for much less. Also, the 640GB WD hard drive will outperform your current hard drive, since it has a high aerial density of 320GB per platter. I'd guess your current hard drive has an aerial density of 125GB per platter, or worse. However, the only difference you'd see from a hard drive upgrade would be a slightly faster boot time for Windows, the levels in some games might load a bit faster, and you might be able to transfer a huge file faster by a few seconds.

This is why, in my opinion, you'd be much better off putting that money into a better graphics card (if this is a gaming build), or more RAM or a better CPU (photo or video editing build). Remember that once you load your game or program from the hard drive, it will pretty much sit idle and the other components will have a much larger impact on your performance. (Note that if you have too little RAM, your hard drive may be forced to stream data to and from the RAM as needed, which will be very detrimental on performance. Of course, the easiest and best solution to this is to buy more RAM, not a faster hard drive.)

Also, I see someone mentioned solid state disks (SSDs). SSDs use memory similar to the memory found in a USB thumb drive. The huge advantage of SSDs is that they have nearly instantaneous access time, typically 0.1ms. However, at this time they have too little storage, too slow transfer rates, too high failure rate, and a much too high price for them to be recommended for a typical user.

Edited by stettybet0, 07 September 2008 - 05:34 PM.

[DA IMP]

stettybet0:

Thank you for your thoroughly helpful reply.

So, you're confirming and elaborating...

SCSI = too expensive and troublesome with no significant difference on speed. Discarded.

SATA 3GBs = Difference with SATA 1.5 doest not apply in practical usage yet. It's more of a "future investment." So, it shouldn't be a decisive factor right now. SATA 1.5 is just as acceptable thus.

other ATA are just a thing of the past. Outdated, slower.

SSD, I never even considered. Access times mean nothing when your actual bandwidth is so slow (anyone that has moved several GBs to a pen drive can testify to this). And yes, they seem a lot less durable.

Now, about aerial density...

I haven't seen that info around, for the most part. It's hard enough already, that a lot of sellers don't bother listing seek (or even rotational) speeds. Trying to get these is nigh-impossible, I think.

What you're saying, very basically, is that in some cases, bigger HDD means faster, 'cos there's more GBs in the same platter?

Maybe I should clarify this again, and elaborate. I'm trying to limit the budget here. I don't wanna spend more than $50-60. A big HDD is not what I seek, just a fast one. Maybe they go kinda hand in hand...

And you have to consider that, to me, spending U$S80-100 instead of 50-60, is a way bigger difference. First of all, my currency is worth less a third, compared. I make U$S800 a month, tops. Gross, before taxes.
Second, since this clearly means I don't live in the states, I have to ship the thing in. I have to consider shipping costs (so, $100 becomes U$S120+)...and import taxes. Which are 50% of the item's value.

Why don't I buy in my own country? The very few places that have anything over 7200RPM, are so expensive than buying it from a seller in your country is still a bargain, after currency exchange, shipping and taxes......

Back to my PC build...

What I have right now, is an old ATA 40GBs as main disk, and the 250GBs SATA 3GBs, 16MBs buffer (which model was listed, for further reference).

I'm making a major upgrade, that will be pretty much a new build. The 250GBs HDD stays. But I don't wanna make it my main HDD, even if it's much faster.
I'd rather get rid of the 40GBs one, and get a fastest one as main disk...While keeping the 250GBs acting as my backup and bulk storage.

I don't wanna use the same physical unit for both things, 'cos I like to keep the 250GBs unplugged most of the time. I only plug it for backups and moving tons of stuff all at once. Oh, and stay offline while I do that.
It's honestly the best way to keep the data safest. That way, all threats (glitches, viruses, intrusions, power surges, whatever), have a much smaller chance at ruining the really vital data.
Keep in mind that I tend to store pretty sensitive info in there, not just a bunch of videos. Data from clients, work, and so...

On aerial density. Right now I'm still looking for small SATA 10k RPM stuff. WD Raptor. Either 36GBs or 74. I assume 74GBs is gonna be faster, by dint of aerial density, and that all models of the same size must have the same aerial density, considering they're same brand and all of the same (Raptor) line...
Am I right?

In the end...aiming for that (SATA 10k RPM, 36-74GB Raptor), will I get a significant difference with small-size (80-250GBs), SATA 7200RPM? I can get SATA 7200RPM around here no problem, with decent pricing and variety.

I know that boosting HDD speed is theoretically only gonna help me on loading times, not overall performance... But I wanna do it, based on the following premises:

1) The HDD is the slowest thing on the PC, always (ignoring opticals/USB/floppy/whatever of course). So, you speed that up, and the whole system benefits from it...the old logics says "a group moves at the speed of its slowest member."

2) This is a primary Windows build. I may dual-boot Linux, but the heavy usage will always be Windows. And let's face it, Windows sucks. It makes a totally excessive HDD usage.

a) Its loading times are awful. It greedily devours the virtual RAM, overtaxing the HDD, even if you have tons of RAM. Regardless of how much free real RAM you actually have (checking this with all manners of software)...even if you have 1.5GBs and everything indicates you're using less than a third of it...the swapfile is busiest at work all the while...

b) After a certain while since your last clean install, it begins slowing down, and leaning more and more on the swap, until it's used for every last thing, and the computer spends several seconds frozen while the swap is being worked all over the place.

So, to make a dent on the toll those tendencies take from the overall performance, I try to speed up the HDD.

The rest of this new build goes like this, roughly: 2x1GBs DDR2-800 kit (working at true dual channel), Athlon 3800 dual-core, 2x512MBs dual-gpu GeForce card.

It's meant to be an overall fast, solid system that can do pretty much anything smoothly, with an ample capability for graphics...since I play lots of videos and DVDs, toy with graphics and design stuff, and would also like to play some of the upcoming high-profile games smoothly.

I'm an exigent user, and work heavily with computers. I want something that performs greatly, with both simple and demanding tasks.

As you can see, good money is being spent on all aspects of performance.

This is actually still a low-budget plan for me, 'cos as I import all this stuff, I can sell the old hardware locally, at prices that will allow me to recover most of the money.
And that's without taking advantage of anyone. I actually made all these calculations assuming I sell everything on the cheapest price for the market.
For once, global economics can get to favor the little guy.

As an addendum to that: I'm bracing myself for the likely possibility that the "HDD speed boost" won't be very noticeable. I can accept getting just a small boost, if the total spent on HDD (after old part sales) amounts to U$S25-30 or so, and I get a bigger HDD in turn (I can sell my old 40GBs on U$S30-40 around here)...
But if that total spent on HDD amounts to U$s80+, it stops looking like an investment and starts looking like a bad move.

'cos I really won't be needing more than a few hundred GBs anytime soon. 40-80GBs + 250GBs is plenty enough, and will be enough for a long while.

I hope this paints the whole situation more clearly.

Thank you all for your help once again.

[stettybet0]

To further elaborate on aerial density as you requested:

You are correct in assuming that there is a general trend in which as the hard drive capacity increases, so does aerial density. Progress in aerial density is what has enabled hard drive capacity to increase over the years. In order for a hard drive to have a high capacity it must have a high aerial density. You aren't going to be able to make a 1TB hard drive with 50 platters of 20GB each. This leads me to my next point. Not every hard drive of the same capacity is equal. Using 1TB hard drives as an example, some have four 250GB platters, and some have three 333.3GB platters. The hard drives that use the 333.3GB platters perform much better. The Western Digital 640GB hard drive I spoke of earlier uses two 320GB platters. This makes it a better performer than all of the 250GB/platter 1TB hard drives and it even outperforms some of the 333.3GB/platter 1TB hard drives in some instances. This is due to it having only two platters, as fewer platters also equals increased performance (as well as less noise and heat).

Western Digital also has a 320GB version of that hard drive with just one 320GB platter. With everything I told you so far, you'd probably be led to think that it would be the fastest hard drive of the ones I've mentioned. However, Western Digital intends for this hard drive to be "mainstream" (put into the budget builds of Dell, HP, etc.), so it must be very quiet and cool to reduce customer complaints. Therefore, they purposely made the drive slower in order to accomplish these goals. I guess the moral of this story is that even if something sounds good, you should do some research to make sure there aren't any caveats.

So, I guess you could go with the small capacity Raptor if you are only buying it for the purpose of shortening load times. But, I would recommend going with the 640GB WD hard drive and selling your other two. It would outperform them both and give you more hard drive space. You say you won't need more hard drive space, but you also say you want to play the latest games. Some new games are requiring upwards of 15GB of hard drive space. It is just a better investment, in my opinion, to go with the fast, large hard drive than the fast, small hard drive.

To go off on a tangent for a second here...

What two GPUs are you planning on using in your dual-GPU configuration? I ask because often people make the mistake of using two low-end cards in a budget build rather than one mid/high-end card (which will outperform the two low-end cards every time). For example, many people make the mistake of getting two 8600GTs, while one 8800GT will outperform them by a lot. Also, the 8800GT is roughly the same price, and when you factor in the increased cost of an SLI (or Crossfire) capable motherboard, it is actually cheaper.

Also keep in mind that the Athlon 3800+ is scraping the bottom of the barrel here. It is the absolute minimum requirement to run Assassin's Creed, and it will not be enough to run new games.

Unfortunately, if you are looking for a computer to run future releases, then you may need to re-evaluate this build.

[DA IMP]

I understand your idea on aerial density. It's an important factor I'll keep in mind for future reference. At the very least, I'm learning something new. I have a great deal of rounded knowledge on the matter, but it often doesn't reach into such specifics...I'm more of a software guy, at that, too...

As I said, on disks of same size, brand, model, RPM and interface, I'm assuming there's no difference in aerial density. Raptors are supposed to be some of the fastest models out there, so that's ok for me.

To regroup a bit: How much would you say aerial density alone adds to a drive's speed? You're already saying it means more than rotational speed, which already, I assume, means a good deal (25% or so, from 7200 to 10k?).

Low budget has to remain low budget, and I won't sell two HDDs to buy just one. I explained why I want to keep two HDDs, the largest one (which doesn't have to be fast) remaining a backup & storage drive. May seem excessive, but in my own experience, the best way to keep data safe, is to keep it physically safe. Away from networks and everything else, tucked in a corner.
I'm actually considering a SATA bay so I can take the 250GBs HDD in and out with more ease, for that matter.

You're right that this isn't the main factor...so, breaking considerably out of the budget, for something that could still be marginal (IF better than focusing solely on RPM)...is just not the way I wanna go yet.

About the latest games... Maybe I should've put that differently. I say that now, but in reality. I doubt I'll have the time. I want an over-all strong build, and I also want the occasional smooth gaming. I won't be playing lots. I'm not even close to a real gamer these days. Haven't been for years. The only games I'm looking forward to playing really, are Blizzard's Starcraft 2 and Diablo 3. Since they aren't even out yet, I'm assuming they'll require a strong build.

So, as it won't be a ton of games, even if each one needs 15GBs, I should be doing fine. I'm aiming for a 80GBs main drive, not to stay in te 40GBs range, after all.

I'm also considering a 5000+ instead of a 3800+. I just got the 3800+ for a pretty low price, so I was gonna keep it. I could sell both that one and my current Sempron, and pay for a 5000+ without much of a difference.

Also...no dual cards. I said card. Should've been more specific. eVGA nVidia 7950 GX2. Don't have the specs with me right now, but it's a dual-GPU, each GPU with its own 512MBs of DDR3 RAM. I'm no graphics expert, but a card that strong should excel at most anything I can throw at it.

So, do you think I could add anything to this build? Aside from considering a 5000+ CPU?

Bear in mind that, modesty aside, I have an uncanny ability to squeeze every last drop's worth of performance from a system. XP and a lot of other software runs smoothly and flawlessly in my systems, with a chunk less of even the minimum recommended. I routinely make them outperform computers with more than twice the RAM and clock speed.

What I'm trying to say with that last bit, is that I won't abandon all hope of the new build surpassing the typically expected, just 'cos it's relatively short on the CPU.

So...despite the apparent contrariness here and there, I'm appreciating your input, and doing my best to add your expertise to mine. I have my own takes on stuff, but there's nothing better for progress, than someone challenging and fixing your ideas heh.

[warriorscot]

Velociraptors are good but expensive and because of the high speeds less reliable with a shorter operational lifetime than a slower disk, given your budget I would not recommend a 10k drive. In terms of importance density is by far the most important, there is also an elusive quality with some drives that just make them faster and its usually a combination of small things from build quality to the performance of the hard drive controller. If ou consider density for a moment by adding more data into a smaller space you make it easier for the disk to read it so it doesn't have to move as quickly, in that way it is far more important than rpm as it not only increases speed but reduces wear and tear on the drives some drives will be lucky to last 3 years some will last well beyond 5 a good way to judge this is the warranty length if it is 5 years the drive is well made and will last a minimum of 5 years in most cases and usually far longer.

The difference in performance from 7200rpm to 10000rpm is nothing close to 25% in the real world, normal performance difference is usually a maximum of 5% and it more often than not swings the other way with it being 5% worse than a slower drive. High rpm drives are designed and used for very specific things, normal computer usage and most gaming is not one of those things and the velociraptors are better than their predecessor in that they are more useful in general but not by enough to make them a recommended buy to anyone who doesn't have cash to burn.

What you need to do is read reviews and find the best current drive on the market which is as often as not in real world performance a 7200rpm sata2 drive, Samsungs held the crown for a long time but were as rare as hens teeth to get the good ones but I think the seagate drives are king of the hill for the moment but you would have to double check.

SATA2 is the standard, its future proof and you should never as a rule buy into old technology SATAII drives have also been getting better with technology advances SATA1 drives haven't. On newer Intel based systems you will also be able to use AHCI which enables full NCQ on SATA hard drives greatly improving performance and stability.

On the CPU side AMD is great and cheap now but if you can go Intel on a new system you should given their power and low price, if you are stuck with an older AMD system then the 5000+ is the way to go the 3800+ is really not enough it was pretty much the first proper dual core and its an old warhorse now.

The GX2 might not be the best way to go, newer is always better even if it has fewer cores or less memory 9 times out of 10 the newer core designs will overcome that difference. You really want a dx10 capable GPU and preferably one with CUDA capability so at least an 8 series Nvidia or 48xx from ATI either will beat a GX2.

With your disks its definately better to just use one disk, if you need backups a removable HDD is not the best way to go. I would keep everything on optical disks either DVD-Rs or back everything up to a few DVD-RAM disks and make multiple copies. You are more likely to toast it disconnecting it from the system as you are to get a problem with a power surge or virus and you should be well protected against either of those anyway surge protectors are cheap and AV software is free.

If you have a decent amount of ram HDD performance in normal operation is minimal in its effect, you only see it really on what i call "big reads" large file transfers from things like games and video editing etc. even on those tasks different disk characteristics will have different performance effects. For example in a game you want to be loading things quickly but not necessarily for very long which means that high rpm drives may never get up to speed and the high density drive comes out on top even though it is slower as it doesn't have to move as quickly or cover as much of the disk to read the data.

I'll finish the ramble but basically if someone asked me right out what they best drive to buy right this minute is I would say a barracuda 7200.11 500gb drive. The 5 year warranty on its own is the best reason, but if you get one make sure that the warranty applies outside the place you bought it, not hard to check but its something you need to check for all your parts.