Hi I have recently built a new system - and happy to say all worked ok first time round. System Spec: MSI K8N Diamond NForce4 SLi Athlon 64 3700+ 939 XFX GEForce 7800G 256Mb OCZ PC3200 DDR Dual Channel Gold 2x 512Mb Coolermaster realpower 450w Was using the system ok for 12 hours, but found that it would not boot past the bios screen after that. I checked all connections - and found that if removed 1 stick of memory - was able to boot again. I presumed was bad memory so have returned both sticks to the store. After installing an unknown 512Mb to use until OCZ is tested i have found that again after about 12 - 13 hours machine will not boot. LED Indicator lights on Mobo tell me a memory failure again :-( Has anybody seen this before - thanks in advance Blue Scampi.