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I have an old PC, which has this motherboard ASRock 775i65G and it has currently 512M RAM. It has 2 of Apacer DDR 256Mb PC3200 (77.G0639.9CJ)

I want to upgrade the RAM into 2GB (which is the maximum capacity) and I found some DDR RAM which differs only in CAS Latency. The above RAM has CL 2.5 and these that I found has CL 3.

Will these RAM be compatible with my PC, or I have to find RAM with CL 2.5 ?

yaylitzis
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  • I don't think the latency will be an issue, I think you just need to make sure it's the right speed. – Tim G. Mar 22 '17 at 10:54

2 Answers2

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Since you are replacing both of the sticks, you won't face an issue with the timing (CL).

Just pick the fastest speed 1GB sticks at (400MHz) for maximum performance and it should run flawlessly. The CL timings/frequency problems usually occur when you want to use different DIMMs which have not the same speed/timings.

This results usually in the BIOS selecting the slower values in order to ensure stability (even if some good quality RAM can run faster than it's reference values)

Don't forget that if your machine can run 2GB max of RAM, it usually means that it can take 1GB per slot, you should not try to get 2GB single DIMM since you will loose dual channel (activated when you use more than 2 DIMMs) and it will probably won't work !

Neil
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If you have modules of different speeds and different CLs, they will work together, but at the slowest speed and highest CL.

Example:

Module 1 - 256MB, 400MHz, CL3
Module 2 - 512MB, 333MHZ, CL2

Overall, the settings will be 333MHZ, CL3 for both modules.

Note that good quality modules can do 400MHz/PC3200 at CL2.

If you just replace the module, there should be no problem at all, unless you manually set an incompatible CL value in the BIOS.

Overmind
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