I've had a Gigabyte GA-8S655FX Ultra motherboard for around 2 years with 2x 400MHz 256MB memory modules running in dual channel perfectly. I recently bought another two 400MHz 256MB memory sticks bringing the total RAM to 1GB. But since I did that apps crash constantly and Windows quite often reboots by itself or gives me the blue screen of death. If I remove the two new memory sticks everything is fine. I formatted Windows and now it runs slightly better, but still with tons of problems. I tried using just the new sticks and removing the old ones and it also worked fine. It looked like the problem was only when all 4 memory sticks were in. I downloaded Microsoft Windows Memory Diagnostics which creates a bootable CD which runs 11 tests on the memory - and sure enough there were problems. I then started a series of tests to try to isolate the problem:
1. I tested each memory module individually, one by one. All passed.
2. Thinking it was maybe one of the memory slots on the motherboard, I tested one of the memory modules on each slot individually. All passed.
3. I tried 2 memory modules together. All tests passed.
4. I tried 3 memory modules together. All tests passed.
5. I tried 4 memory modules together. TWO TESTS FAILED!!!
6. I took another 2 x 400MHz 256MB memory modules from another computer, and tested them with both my 2 old sticks and 2 new sticks - BOTH FAILED!!!
7. I tried a 512MB stick with both my 2 old sticks and 2 new sticks - BOTH FAILED!!!
Basically, from these tests, I determined that it doesn't matter which memory modules I use, what their size is, or which memory slots on the motherboard I use - everything works fine until I put 1GB of memory in - then the ERAND and Stride6 tests fail and Windows works HORRIBLY. My motherboard was top of the range when I bought it - so I don't know why it wouldnt be able to handle 1GB RAM. The BIOS is picking up the memory and it's passing the boot up memory test. I have a 2.8 GHz Pentium 4 CPU (800 MHz FSB, 478 pin). '
Any ideas? Thanks