Confused, Random restarts turned to failed startup

[Shopsmart86]

Hi there, I recently was having problems with my pc randomly restarting. My computer was running fine up until a couple days ago where I would sit in the desktop no problem but after loading any game usually ended up in a random restart. The weird thing is they seemed to happen at the same intervals (after 10 minutes or 12 minutes etc, I never kept exact track but it was getting to the point where I could see a pattern aka I didn't think it was a faulty power supply at first). So first I thought it was the video card acting up as it was overheating due to it happening with games running, so I downloaded Everest home edition and it stated the gpu was at 85C, which for most people is on the high side, so I'm told I don't really know. So having 2 other graphics cards I installed a different one only to the same result it would go up to 85 degrees C just idling in windows. However, I tried to load games and minimize to see if it changed and there wasnt much of a change, so that led me to think the motherboard is being a turd, however since everything booted up and ran fine I wasn't convinced that was the problem, as the fan was active on the gpu and cpu, and the add-on soundcard was working, along with obviously the ram, and no beeps or anything on boot. So I decided to format as maybe I thought I got a virus causing the drivers on the gpu to go out of control and overheat or something (I don't know). After formatting the HD Ntfs standard, I call my dad to check on it as I was at work and he told me at the windows install screen (or most likely a dos screen before it) there was a pfn_list_corrupt which I looked up leading to possibly being a ram error. So I had him start the format again and Seeing as I had 2x2gb pc 6400 in a DC setup and another brand of the same spec in the other channel I took the older ones out, and that night was able to install windows, and update some drivers and stuff and turned it off and went to sleep to finish the next day. I come home again and try to boot up and it gets to the windows xp load screen and will shutdown or go into what seems like sleep mode, not nessecarily reboot, shutdown or load windows I lose visual signal on the monitor but it keeps running, and after trying that a couple times I decided to run Memtest86, which I have been running for about 6 hours now without an error yet. So I am absolutely stumped, sorry for the long post and I appreciate any help anyone is willing to give me. Thank you very much.

My specs:
-First Gfx card in the system was a Nvidia 9600 gt
-Second test card was a Ati x1950 Pro
-Current third card is another ati x1950 I believe (got it from a friend, this was only after I was able to get into windows the one night after install)
-BIOSTAR TForce TP35D2-A7 LGA 775 Intel P35 ATX Intel Motherboard
-OCZ Platinum 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) (The old ram I removed)
-Crucial Ballistix 2GB (2 x 1GB) 240-Pin DDR2 SDRAM DDR2 800 (PC2 6400) (The current ram)
-Western Digital Caviar Blue WD3200AAJS 320GB 7200 RPM SATA 3.0Gb/s 3.5" Internal Hard Drive
-Rosewill RX630-S-B 630W ATX12V v2.2 & EPS12V v2.91 SLI Ready CrossFire Ready 80 PLUS Certified Active PFC Power Supply
-Intel Core 2 Quad Q6600 Kentsfield 2.4GHz LGA 775 95W Quad-Core Processor
-Windows Xp Home Edition

P.S The Everest recorded temperatures of:
35 or so degrees C for my Mb
I think 30 for the HDD
And 12-15 Degrees C for my processor (which I don't know if that's good it's low as in not transferring properly, but I doubt that as it was constantly recorded as low and would increase under load I also increased the failsafe shutdown temp to 80 degrees celsius which I'm sure the cpu doesn't reach before even finishing startup of windows, or that I can eliminate that as a factor, unless the Mb is messed up and recording wrong temperatures)
Thanks again.

 

[Hefemeister]

Your CPU is definitely not showing the correct temp unless you are running it in a room around 0C or 32F.

Is the heatsink fan running on your cpu?

Have you remounted your heatsink?

If you can get into bios what temps does it say?

 

[Shopsmart86]

My heatsink fan was running, I was going to try to remount after work I think I stretched one of the clips when installing because of a weird design so maybe it came lose with vibration a little bit, I'll check that and the bios temp when home, thanks. I think Everest said the fan was running at 2450 rpm, if I remember correctly.

 

[Shopsmart86]

Came home, took the whole thing apart to find my proc covered around the outside with jet black dust clots, so I cleaned it all with alcohol, new grease etc. And it works just like new, currently. I just hope the grease is dispersed well but I'll only find out in time, thanks for the help I've never seen that much dust before on my other cpus so I didn't think that was it, but I figured since you had an idea couldn't hurt to take it apart. Thanks again.