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Upgrading my RAM


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#1
hifiguy

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I own a Fujitsu C-7651 laptop want to upgrade the RAM. It has 256mb that are fixed/non-removable and I can put a maximum of 512mb module into one slot. This machine takes a PC133 module with 144 pins - SDRAM/SODIMM. I have seen modules that fit this description that have 4 chips on each side and others that have 8 chips on each side. Which type do I need for this laptop or can I use either one? What is the difference between the modules with twice the number of chips on the board? Thank you.
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#2
phillpower2

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Hi hifigu :)
Use the Crucial system scanner tool to get the recommended Ram details for your laptop;
http://www.crucial.c...:20100901184937
There is no need to purchase from there simply make a note of the recommendations then shop around for the best deal.

What is the difference between the modules with twice the number of chips on the board? Thank you.

You can google this question but you may find this explanation The difference is the chip density used on the modules.
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#3
hifiguy

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Thanks for the reply, but the Crucial link does not even have my model listed(Fujitsu Lifebook C-7651). I've used other memory configuration tools that do and I have all the specs I need so I've already begun shopping for the best price. The question remains: do I need a board with 4 chips on each side or one with 8 chips on each side? I've seen both advertised and pictured on different companies sites and on eBay with the exact speces that I need: 512mb, SDRAM, SODIMM, PC133, 144 pin, 3.3v, Sync, Non-ECC, Unbuffered, etc.. Or does it even matter? Maybe I can use either one? Anyone have an answer. Please explain about chip density. I thought that was basically the amount of memory.
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#4
phillpower2

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Thanks for the reply, but the Crucial link does not even have my model listed(Fujitsu Lifebook C-7651). I've used other memory configuration tools that do and I have all the specs I need so I've already begun shopping for the best price. The question remains: do I need a board with 4 chips on each side or one with 8 chips on each side? I've seen both advertised and pictured on different companies sites and on eBay with the exact speces that I need: 512mb, SDRAM, SODIMM, PC133, 144 pin, 3.3v, Sync, Non-ECC, Unbuffered, etc.. Or does it even matter? Maybe I can use either one? Anyone have an answer. Please explain about chip density. I thought that was basically the amount of memory.

A 512MB stick of Ram that has 8 chips on either side will be 8X32MB = 256MB X 2 = 512MB
A 512MB stick of Ram that has 4 chips on either side will be 4X64MB = 256MB X 2 = 512MB
A 512MB stick of Ram that has 8 chips on one side only will be 8X64MB = 512MB
As long as the Ram settings are the same there is no difference and either type will suffice.

NB: The Ram I could find on ebay clearly states that the images were for illustration purposes only so you could end up with any variation of 512MB stick of Ram in any events.
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#5
hifiguy

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Ok, thanks. That makes sense. Any of the chip configurations should work if the specs and sizes of the board are the same. I do know that my machine wants a "low density" ram board. What exactly is that referring to? Does 4 chips on a side mean that is a lower density board than one with 8 chips on a side? Thanks again.
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#6
phillpower2

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Below is an explanation that I found;

Many only consider SPEED when purchasing memory and often neglect an important fact that memory DENSITY is actually even more important!

So why memory DENSITY is so important? Is it related to your system when upgrading? The answer is YES!

If your system is designed for accepting DDR (Double Data Rate) memories of 184pin DIMM (usually desktops) or 200pin SODIMM (usually laptops) built, for your system to fully recognise 1GB capacity per memory slot, you need to use 'Low Density - 64Mx8 config' 1GB module. If you use 'High-Density - 128Mx4 config' 1GB module, your PC may only recognise it as HALF the size at 512MB or most of the time it will not work.
How to tell if your 1GB module is a low or high density module?

All low density 1GB modules are made with 16 chips (8 chips on each side) using 64Mx8 device.
All high density 1GB modules are made with 16 chips (8 chips on each side) using 128Mx4 device.
It costs memory manufacturers almost the same to produce Low Density 1GB modules which have 100% compatibility with all systems on the market, comparing to producing high density 1GB modules. So why would manufacturers be so foolish to produce high density 1GB modules which only have 10% compatibility with systems on the market? The reason is simple, because high density 1GB modules are mainly manufacturing process rejects/seconds that cannot be made as a low density modules. It is very much like Intel CPU, those CPU that cannot be made as Pentium 4 CPU become a slower bus Celeron CPU instead, by a down-binning process.
High Density module is by far much slower than Low Density module at same speed rating say PC3200/DDR400. A lot of users have fallen into attractive CHEAP PRICE trap by High Density module sellers and have complained that they are either VERY SLOW and/or will not run at all and sellers won't accept return!
High density modules are FAR CHEAPER, less than half the price when compare with low density modules and hence high density modules will NOT work on 90% of today's PC chipsets that require and can only use 'Low Density - 64Mx8 config' 1GB modules.
In summary:-
LOW DENSITY modules have 100% compatibility with ALL systems and ALL chipsets.
HIGH DENSITY modules only have 10% compatibility and are VERY SLOW.
This is also why almost all Branded-Name systems such as Apple/MAC, Compaq/HP, Dell and IBM only uses LOW DENSITY modules.
However 90% of eBay are plagued with High-Density 1GB modules at very low price, and you will be wasting your precious time and money having to return those high density 1GB modules to your seller for refund. So AVOID those 'High-Density - 128Mx4 config' 1GB modules which is usually UNBRANDED and is NO NAME!
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#7
hifiguy

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Perfecto! That exactly answers my question. Clearly I need to buy a module that has 8 chips on each side instead of just 4 on each side. Thank you very much!
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#8
phillpower2

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You are welcome, good luck with the upgrade :)
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