A while ago I built a system for my brother from spare parts and parts going cheap. At the core of the system is a DFI LanParty UT RDX200 CF-DR, an Athlon 64 3200, 1GB of Ballistix PC4000 DDR and a X800GT AIW.
He doesn't use the system for games and it has served him well until now. The previous load of Ballistix ram had been faulty and was replaced by crucial.
At the moment the system is very unstable and we are having trouble restoring an Acronis True Image file of the drive I created in January. It is failing memtest 86+ with both the Ballisitx ram and some Corsair Value Select stuff that was previously known to be working. It is getting a lot less errors with the Ballistix though (2 errors after 27 passes). In fact it often wont boot properly with the Corsair. I have had the Ballistix at the recommended 2.8v and the Corsair at stock and have not been fiddling with ram timings. I have done CMOS resets in between changes and I have flashed the BIOS to the last official release.
Am I unlucky with ram or is it likely to be the motherboard?