Problems with random reboots

[Jayfaas]

I currently have the following setup:
Intel Core2Quad Q6600@2.40GHz
DFI Lanparty UT P35-T2R motherboard
4.0GB of G.Skill RAM
WD Raptor 10,000rpm hdd
PC Power and Cooling Silencer 750 EPS512 PSU
XFX GeForce 8800 GTS 512

For some reason I am getting random reboots and I cant find out whats bad. The HDD came from the last build I had and I just swapped it into this one and its been fine, but one day my computer just started randomly rebooting and I get no message. I turned off the "Automatic restart" in the control panel settings and it doesnt even give me a BSOD. I checked event viewer and got nothing. There is no trigger as well, although it seems to do it more when im playing Counter-Strike(i know its old). I dont think its a heat issue because I grabbed one of the garage fans and have it blowing right into the case and it doesnt seem to help. Sometimes it will reboot as soon as I get into the game and other times it will let me play a few rounds and then reboot. I did notice that if I run prime95 on the blended test or the large FFT test it reboots immediately, but if I run the small one I can run it with no errors. How can I troubleshoot this properly so I will know which component to replace? I already tried a new PSU and it had the same problem. Put one RAM stick in at a time, made sure and cleaned off all heatsinks, cpu and gpu are running at good temps, system is not overclocked...ran crystal disk on the hard drive and it said it was healthy, ran memtest for a couple hours with no problem, took out the sound card. My only guess right now is that its the motherboard, but how can I be absolutely certain?

[mockingbird]

It's your 8800 GTS I believe.

Test with another graphics card to confirm.

[zanzabar]

when my SSD started to die it did that. i doubt it is the graphics card as those normally show artifacts, or discoloration when they force a restart from bad vram, or blue screen when the gpu is dieing. i would start by changing the HDD out if you have a spare, then test each stick of ram (what fails with the large FFT test.)

[Jayfaas]

If the HDD was bad wouldnt Crystal Disk pick up on it? Also I wouldnt THINK it was the GPU due to it also failing with Prime95 immediately, unless it has a huge tie-in with the graphics. Ive done the ram swap and did one by one and tried different slots with no success.

[zanzabar]

crystal disk will not detect if the drive is dieing or has corrupted windows files, it can detect bad sensors in free space.

[Jayfaas]

Well I am about to upgrade that computer. What should I upgrade as far as HDD that I can use on my board now and on a future board when I upgrade here in the next few weeks? I heard SSD was the way to go now, and I saw an Intel 120GB 520 series one there. Should I get that or is there something that is a better deal for the money that I should get? I dont need anything over 120GB because I will never fill that up. Maybe if that one is okay I can go pick one up today and put Windows XP on it tonight and check it out to see if that fixes the problem. Will that work with my DFI Lanparty UT P35-T2R board? I am not sure if SATAIII is compatible with my board or not.

[Jayfaas]

any other suggestions?

[zanzabar]

on the SSD, do not buy anything with a sandforce controller (that includes the 520,) they are slow, unreliable, and really slow. get something with a marvel, lambd, or samung controller. i think that the samsung 840 pro is the best ATM. sata III is backwards and forwards compatible so it will work fine on your board, i have an M4 running on my old x38 lt.

[Jayfaas]

Now I am having real concerns. I just downloaded 3dmark06(since im still running XP/DX9 I cant get 3dmark11) and it ran all the tests fine without rebooting. what is the deal? If I start Prime95 on blended tests or large FFT's it reboots immediately. If I launch CS:GO it may play a few minutes or reboot as soon as I get in game, but I can run 3dmark06 which puts all kinds of tests on the system and not fail?