Weird memory problem...

I had 768mb of ram before i installed my new Athlon XP. After the installation was complete, i reinstalled my ram and booted up my computer. At the boot screen, it showed only 512mb of ram. Hmmmm, i take them out 1 by 1 and test them to see which one isnt working. I set one in Dimm1 and it boots showing 256mb of ram, fine this one works... I put the second one in, boots up showing 256mb of ram, this one is fine too... I put the third in, no go, wont boot, so i figure i must have damaged it during the installation of my processor. So, i put it aside thinking RMA. About 5 mins ago, i had an idea to try it in my other pc which already has 256mb in it. I put it in, press the power button and boots up showing a total of 512mb of ram.... The million dollar question is, why wont it boot in mine? I tried a multiple ways, dimm1, dimm2, dimm1 + dimm2... still no go. What could be causing this? Could it be the fact that i installed a new processor?

Could you have possibly damaged one of the DIMM slots on the motherboard? Perhaps inserted a DIMM backwards? They are keyed to go only one way, but can be inserted if forced (Don't ask me how I know that ). I seriously doubt it is the CPU. Maybe try blowing each of the DIMM slots out with a can of compressed air. Was you old CPU running at 133 memory bus? Are you overclocking the memory bus? Sometimes boards have a hard time booting at high memory bus speeds with all three DIMM slots occupied even if all 3 DIMMs are qualified to run at that speed.

Geoff

I should have tried this earlier.... such a stupid thing of me, lol. Turns out this stick as a mind of its own... I tried it in my motherboard again and i noticed that it needs to be pushed in... after you clip it. Its weird, i've never seen anything like this... the other 2 sticks go in fine, they clip in and they're good to go, but this one is just weird, plain and simple, lol. Thx for the reply though.