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.
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...
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:
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.