For the last 1-2 weeks, I've begun to bluescreen 5+ times a day It happens in the middle of applications, but also when I haven't even opened anything. Other days, it runs fine for hours on end. I don't overclock. I'm running AVG. I didn't install anything or make any changes before this isht started to happen. Specs: I bought this in March 2010. CPU: AMD Athlon 64 X2 Dual Core Processor 6000+ [3GHz] RAM: Crucial CT25664AA800M16FJ 2GB DIMM DDR2 PC2-6400U DDR2-800 (5-6-6-18 3-24-6-3) GPU: NVIDIA GeForce 8400 GS (16 SP 1.7GHz, 512MB DDR2 2x400MHz, PCIe 1.00 x16) MoBo: ASRock N68-S PSU: Logisys PS480D-BK ATX-500 500W Switching Mode power supply (actually it reads Total Power = 330W, Max. Output = 480W) I am not techie about PCs so please be gentle I read as many forums as I could understand. I've run a bunch of tests now: System Mechanic cleaned up the registry, plus I defragged . I ran HDtune - hard drive checked out fine. I booted in Safe Mode and uninstalled the graphics drivers & reinstalled the newest ones from the nVidia website. (*The machine BSOD'd in Safe Mode, too.) I ran 7 passes of memtest86+ last night (for 8 hours) with ZERO errors. WhoCrashed, comes up with different windows system processes etc., so I understand it's prob. not any one of those, but something else is causing them to fault (conflicting drivers something something? or DLL something something?) I've also run Belarc Advisor, SiSoft Sandra, Speedfan, Fresh Diagnose, and AutoRuns, but to be honest, after pouring over all this stuff, I dunno what I'm looking at. Like I said, a few days ago I didn't know what BIOS stood for. I've checked the event log and error log, and there's a bunch of red icons, but I'm not sure which ones (if any) are really meaningful. Can anyone help me make sense of those? The bluescreen error codes were all 0x0000009c "machine check exception" for a long time, but I think after I some of these diagnostics, they've started to change slightly. I could be wrong. But now I've also seen 10000000a, 10000008e and also 100000050. I've read that " lot of BSOD`s are caused by faulty ram/underpowered psu`s/ overheating/overclocking/dust and debris.", and this is especially so with the "machine check exception" error (it's usu. a hardware issue?). So based on my (grossly inexperienced) attempts at trouble shooting, my thoughts are: 1) I have a dodgy mainboard? <how do I determine for sure? I see no bulging caps, etc.> 2) my PSU is weaksauce? <is there any way to know without a multimeter? the fan seems way louder than my previous comp.> 3) my CPU is overheating or is not receiving enough steady[?] power from the PSU? (how do I check this? the sticker says it outputs 16A on the +12V, isn't this a little low?) 4) the fan on the CPU heatsink also "brrs" pretty loud esp. at startup, but it runs @ c. 4000rpm, so I think is ok. (thoughts?) 5) I have driver conflicts or..? (do I need to manually install and reinstall all my drivers? shouldn't the windows updater take care of this automatically?) 6) Last: one of the anaylsis tools noted that my video card biosis more than 2 years old, and might need updating.. but I'm a little hesitant to "flash the video bios" or whatever, I understand this can be risky. <Any thoughts on this?> If you have any clues as to what/how to trouble shoot next, I would REALLY appreciate your insight! Attached are the most recent minidumps, but I also have earlier ones too, which are probably all "machine check exception 0x0000009c" ones.. So I can upload them, too, if it would help. Please advise! Mahalo.