TR Forums

I have a question reference some RAM i have just purchased, but first some History.

About 4.5 years ago i purchased 1 Gig matched pair of:

TwinX1024-3200C2PRO
CMX512-3200C2PRO XMS3200 400MHZ CL2 XMS3202V1.0.
Lot code:0347153

In an effort to increase my comps RAM i have purchased some more memory of the same kind (well nearly). It seems that the memory i have purchased is exactly the same except for the version number, the new memory is:

TwinX1024-3200C2PRO
CMX512-3200C2PRO XMS3200 400MHZ CL2 XMS3202V5.3.
Lot code:0630223-1

My question is are these compatable with each other, i would have thought so as from the items technical desription they are both the same and retailers never specify versions, but according to Corsair they can't guarentee that will work together and say:

Officially we would not suggest or support mixing memory ......

Has anyone else heard of this problem? What is the difference in the versions and why might they not work together?

BTW. I have not tried the new RAM yet as i am waiting on a new monitor but will give it a try as soon as i can.

Any help appreciated.

Sometimes mixing different types of modules can cause problems with your memory timings, resulting in system instability. Given that the ones you have are the same model (even though different revisions), chances are pretty good that it'll just work.

There is also another potential issue which has absolutely nothing to do with whether the modules are matched or not. Some systems simply do not like to run with multiple double-sided DIMMs on a memory channel; if all of your modules are double-sided (have chips on both sides of the DIMM), you may be affected.

In both cases, the solution is to manually set your memory configuration in the BIOS, reducing the memory clock speed and/or loosening the timings.

After installing the new DIMMs, I recommend that you run a RAM diagnostic (like Memtest86) to make sure things are stable. Don't even try to boot into Windows until you've run at least 2 passes of Memtest86 (overnight would be even better); if the new RAM doesn't play nice, you can corrupt your registry badly enough to render the OS unbootable.

This is worth repeating: I spent a whole weekend messing with the timings and memtest86 just to find the one combo that the system likes. Too slow was no good and too fast was bad also. So be prepared to do some work.

Good luck.

Flying Fox wrote:

So be prepared to do some work.

Good luck.

Thanks for the advice so far but when i purchased the new matched pair i assumed that these modules would be totally and 100% compatible with the modules i already have. If version differences in the same RAM can cause stability and compatibility issues then why isn't the versions advertised or listed when you buy RAM so you can make sure you are getting the same version that you already have. Otherwise how are you ment to expand you RAM, it seems more like a lottery.

If you buy ordinary, mainstream memory with relaxed timings, you can pretty much mix and match with no issues. If you buy premium, "enthusiast" memory you may have issues when combining memory with tight, but different, timings. Different chipsets (or memory controllers in different AMD CPU steppings) figure into it as well -- some are more tolerant than others. Which is why there aren't any warnings -- there are too many variables, and the enthusiasts who buy the memory are supposed to be able to figure it out. Though if you go to the memory manufacturer websites they often have "configurator" pages that can help.

I buy mainstream "value" memory because I don't want to deal with this (especially if a CMOS battery failure means the system later starts booting with default BIOS settings) and the speed difference is generally negligible anyway.

A few years back I bought two sticks of 512MB Corsair XMS-PC3200C2 DDR about eighteen months apart. As with yours, they were exactly the same part number, just different revisions. With a bit of digging, I discovered that they used entirely different memory chips (Winbond on the earlier stick, Infineon on the latter). My motherboard was limited to single channel (845PE) and I was able to use both together at their rated timings with no problems, but I often wondered if they would have worked in a dual channel configuration.

UberGerbil wrote:

If you buy ordinary, mainstream memory with relaxed timings, you can pretty much mix and match with no issues. If you buy premium, "enthusiast" memory you may have issues when combining memory with tight, but different, timings. Different chipsets (or memory controllers in different AMD CPU steppings) figure into it as well -- some are more tolerant than others. Which is why there aren't any warnings -- there are too many variables, and the enthusiasts who buy the memory are supposed to be able to figure it out. Though if you go to the memory manufacturer websites they often have "configurator" pages that can help.

I buy mainstream "value" memory because I don't want to deal with this (especially if a CMOS battery failure means the system later starts booting with default BIOS settings) and the speed difference is generally negligible anyway.

My scenario was a bit different, both sticks were value memory but I bought them at different times and they definitely had different timings. As with any new hardware I would run tests so I caught the error(s) early but it just took a long time to figure the right timings that both sticks of RAM can tolerate.

I read often of relaxing timings...my new memory is CORSAIR DOMINATOR 4GB (2 x 2GB) 240-Pin DDR2 SDRAM DDR2 1066 which runs at 5 5 5 15. I had to manually set the timing and voltage to 2.1 in the bios. What would it mean to relax the timings on it going to 4 4 4 12? or going with higher numbers 6 6 6 18 and what would be the benefit?

With the price of ram so cheap it almost seems like its not worth it to try to match old ram with new...rather save a little more and buy a matched pair of the size you want...just too much trouble to configure and trouble shoot

Relaxing timings means increasing the various delay times, usually to improve stability if running at higher frequency. So 5-5-5-18 is more "relaxed" than 4-4-4-12: you're allowing the memory more clock cycles to achieve each stage of the read and/or write process, at the cost of increased latency.