Computer restarts or turns off during game playing

Could be GPU or CPU overheating, check these with idle and load with RealTemp and Prime95, also the NVIDIA temp monitor for GPU and post results.

Could be the PSU, although this is strong enough and a good brand you can get bad ones. During high load more strain is on the PSU and if it doesnt supply enough power... well as you say "poof"

Ram prolly needs more voltage for 8g.

Or the PSU way be dieing.

Yeah... I'll have to try the temp stuff. As for the PSU if it causes a short wouldn't that cause failure on all components? Every time I run anything other than a game my computer is rock stable.

I'll try to up the RAM voltage to 2.2v...

It is your PSU!

I had the same problem with: Antec Tru Power 2.0 550w, Core2 E6400 @ 3.2, Asus 8800 ULTRA.

I tried everything, but couldn't even find any relevant driver info becoz it just restarts without even memory dumping. I swapped every other component including cpu out.

Solution: New more powerful Power Supply OR, connect a second PSU to one of the PCI-Express power plugs in the GPU. Since i live in a country (sri lanka) where the most powerful psu available is 450w, i had no option but to go this route. But if you live in any part of the civilized world, i'm quite sure you can grab urself a good 600w++ psu and solve all your problems  

Mine is 850w and has the necessary amperage required, at least it should... I tried upping the memory voltage setting to .30. I think that's 2.1v but I'm not sure. Still no good... maybe it is and always has been the psu... it just doesn't make sense...

Things age, so does your psu. If you look at real good psu calculators they include the age of your psu, as capacitors age, get brittle if you will, aging caps=lower power. If you have or can use a different psu, try it and see if its ok.

Take off the side of the case and setup a room type fan blowing onto the electronics. This should tell you if the over-heating is the problem.

I've only had the system for a year... and I don't have a stand alone fan... Guess I can try things with the side of the case off..

Well I tried to play with the side of the case off... The computer started to make beeping noises... So I stopped the game and the noises went away... It makes no sense. The PSU wasn't hot to the touch and the 8800GTX didn't feel too bad... The only heat was the air being pushed out from the fans to the rear of the case but this air has plenty of space to be circulated... Bloody hell...

Still have no idea... Tried underclocking cpu, gfx card, playing with the side of the case... i don't get it... no money to try to swap out components either. fun all around!

Also, SpeedFan is saying that the +12v is only sending 2.3v is this bad? I don't understand it...

Another possibility: you might well have a bad thermal connection in your heat sink mount, so it's not cooling your CPU efficiently. This could happen if you've unmounted and remounted the CPU and didn't do the thermal paste properly for example. You can probably get a utility to display your various system temps for you to determine definitively if it's overheating issue.

I have smartfan, but don't really know how to read it

I have the exact same problem, with the same brand mobo but the am2+ version, the DS3.

The stupidest thing about it, is it only restarts on vista, never on xp, and it specifically restarts on video heavy applications, such as gaming and overclocking. I discovered ways to delay the inevitable, and somehow tinkering with ram does the trick, not the video card :S, such as lowering ram clock speeds, timings, but all in vain. But it did change my restarts from 5-30 mins to 3+ hours. Im currently testing higher voltages and im trying to get tech support from gigabyte, but its taking a while -.- i dont even have a video card that needs a pci-e cable to top it off.

I just set up my old pc with an old killer, asusV9999 6800gt, i was setting up the cables on the damier6000, i turned it on with all installed except some fans to check to see which fans were pluged ok, and the pc was making very loud beeps, and wouldnt stfu until i turned it back off. When i checked the 6800gt, i noticed i forgot to plug in both plugs for the extra power it needed. I will assume your psu is still good, try switching which cables you have pluged into the card, maybe somehow its that since il guess the card isnt getting enough power due to that beeping

I've got all power connections set up right, as far as I know. I'm not comfortable or knowledgeable enough to fiddle with hardware. If this was a software thing I could have figured it out a while ago... I also have an extra plug into a +12v connection on the mainboard for more power.

Maybe my friend who set up the computer for me installed the PCIE cables in the wrong part of the TT PSU? I don't know. I am moving soon so my computer is packed... won't be able to do anything with it until Saturday. I just don't know how to read SpeedFan. I can't understand why it reports the +12v voltage at 5v...