RAM : mixing modules

  John Ross 12:27 07 Oct 2007
Locked

I am updating RAM in two PCs.

One is a 3.4MHz Gigafast motherboard GA-81848PM with 512Mb of PC3200 RAM running Xp. Crucial system scan says there are 3 DDR slots on the motherboard and that I should remove the 512Mb PC3200 and replace with a 1Gb module of PC2700 :
CT12864Z335
Module Size: 1GB
Package: 184-pin DIMM
Feature: DDR PC2700
Specs: DDR PC2700 • CL=2.5 • Unbuffered • NON-ECC • DDR333 • 2.5V • 128Meg x 64.

In fact the motherboard only seems to have 2 slots, and I was unsure of their advice for a slower module. Instead I have purchased :
CT12864Z40B
Module Size: 1GB
Package: 184-pin DIMM
Feature: DDR PC3200
Specs: DDR PC3200 • CL=3 • Unbuffered • NON-ECC • DDR400 • 2.6V • 128Meg x 64

I was comfortable about this decision until i started reading some of the Helproom threads.
My question is :
Was crucial's recommendation of a slower memory module correct, and if so why?
Is this high density RAM OK, compared to low density?
Would it have been better to run 2 X 512Mb RAM modules rather than one 1Gb?
Will I be able to run my old Samsung 512Mb RAM along with the new 1Gb, if so do they need to be in a particular order in the slots?

As this is getting complicates I will submit a 2nd post for the other PC!
thanks

  crosstrainer 12:33 07 Oct 2007

On the speed of memory your mobo will support....If you have it consult the manual, or check the manufacturers web site...Gigafest? Do you mean Gigabyte?

  Stowit 12:47 07 Oct 2007

My 2p, some RAm comes in pairs, that are matched & supposedly run quicker. If you are not refering to 'matched pairs' my guess is bigger is better. AS for high density, it depends on the rest of your hardware. My pc won't run with HD RAM, low density is more compatible. HD ram is usually a lot cheaper. The 'speed' (PC 2700 - 3200 etc) should just be the ones for the mobo, there is no increase in speed beyond what the mobo is speced for, although I believe they my work with the 'faster RAM.' I think it's like puting higher speed rated tyres on your car.

  John Ross 13:14 07 Oct 2007

Thanks, you are right it is Gigabbye.
the mobo does not look like any on their website, and I am guessing it (GA-81848PM) is a cut down bargain version of their GA 81848P models (it has only 3 PCI slots vs 5, and only 2 DIMM sockets not 3). The PC manufacturer Fujitus siemens doesn't have great detail on its website.
Curently the RAM module is PC3200 so presumably the 2nd slot is compatable for this also? If so, then should be back compatable?
to reiterate the issues that I am unsure about :
Was crucial's recommendation of a slower memory module correct, and if so why?
Is this high density RAM OK, compared to low density?
Would it have been better to run 2 X 512Mb RAM modules rather than one 1Gb?
Will I be able to run my old Samsung 512Mb RAM along with the new 1Gb, if so do they need to be in a particular order in the slots?
Thanks again

  DieSse 13:57 07 Oct 2007

The worst thing about mixing RAM with non-identical specs, is that it'll seem to work, but you may get obscure intermittent problems. I would absolutely never recommend this.

Using two modules instead of one has the slight advantage that if one failed, you can continue to run your system on the other one.

  crosstrainer 14:13 07 Oct 2007

Is right, to indentical (matched) sticks are what you want. That board is indeed a cut down version, you can check what speed your memory is currently running at (you would be better off with 2 1gb sticks) by using click here

Download it and run the audit (free) this will give you a detailed report on your system.

  John Ross 22:04 13 Oct 2007

Thanks for everyone's advice.
I installed the 1GB RAM in the first slot, the 250MB in the 2nd : only got 1GB, so swapprd them around.
Maybe I am lucky, but now working perfectly with 1.5Gb RAM : notable improvement on boot up and less delays when switching between programmes.
A good investment so far.

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