Neo 2 Platinum Memory Problem

Question

Hi There,
i have here two PQI DDR400 PC3200 512MB dual-sided, one crusial DDR400 PC3200 512MB one-sided and one crusial DDR400 PC3200 1024MB dual-sided.
Here's the problem:
When i install all the four modules my computer wont bootup it will only give one long beep inducating that there is a memory problem. All four modules where tested separetly with no problems. I have now only the two crusial modules on my Neo 2 Platinum running with no problems.
Can some one help me so i can use all four modules please???????

Answer 1

Assuming they will all work together, it sounds like the BIOS isn't set up properly, or the board isn't detecting the speed correctly. When installing more than 2 dimms, most boards, due to the memory controller on the CPU, will set the RAM to the 166 divider, or DDR333. Generally it will also set them to the 2T command rate. 
If you have a Winchester core you will more than likely need to run DDR333 with the 2T setting. On a Venice you may be able to get away with DDR400...I know on an Opteron you can do DDR400 with the 2T command rate easy enough...I will assume it is probably the same with the newer cores as well.
Again, IF they all work together (mixing and matching dimms may not always work), you may just need to set the BIOS up properly. Pop in the sticks that work, go into the BIOS and set the RAM to the 166 divider, and then make sure the command rate is on 2T. Be sure all the RAM can run the timings that are set in the BIOS. Save and exit. Then power down and unplug the PC, pop in the other stick and see what happens.
If that doesn't work, you can try different slots, or an even a lower RAM divider (probably won't make a difference). IMO, if all the settings are correct and it still won't work, I would guess that mixing the RAM is the problem. I have seen it happen - I have also had weird RAM configs work perfectly, so it is kind of hit or miss...I hope some of that helps, good luck.