My first PC build. What a nightmare! I've learned to fix some problems myself with the help of these forums. Now I'm stuck. I've had to reinstall vista 4 times on 3 different sets of hardware because of defective MOBO/HD/video cards. Finally I have hardware I think is functional and now this. The BSODs started only when running 3D games /applications ie WoW or solidworks. Now they have progressed to random bsod while not doing anything specific. System specs: Vista home prem 64 GA-ep45ds3l MOBO HIS 512M radeon 4670 550W Rosewill 2x20A rails 2x4G Gskill 1033 Q9300 quad core I've: run scandisk, windows memdiag tool, Un/Reinstalled latest video & chipset drivers, uninstalled MOBO utility SW, ran CCleaner, flashed bios & loaded deafaults, and played with BIOS settings to no avail. I can make the problem worse, but not better. There is a bios setting for 64bit HPET (manual said use for vista 64), but that didn't help. The Logitek drivers for my wireless keyboard were flakey, so I updated and that seemed to amplify the problem. I still need to burn memtest and run it, and I haven't installed Antivirus sw yet as I've only had the system a week and haven't been doing any unusual DLDs. I'm getting tired of reformatting. Anyone had any luck with running windows repair from the install disk? The fact that I had no problems initially until running 3D stuff makes me think the problem must be drivers rather than memory. I get cryptic msgs from bsod such as page fault in non paged area, IRq not less than or equal to, blank, and various hexidecimal numbers. There are over 1000 errors in event viewer such as: //./root/CIMV2 SELECT * FROM __InstanceModificationEvent WITHIN 60 WHERE TargetInstance ISA "Win32_Processor" AND TargetInstance.LoadPercentage > 99 0x80041003. Whatever that means. Hopefully there will be a light bulb somewhere in those attached memory dumps. Anyone? Thanks.