System auto powering down

[nerdynick]

So I just built a new system a little while back and since then I've been having weird problems where while playing a game or doing something intence the system will just power off on its own.

At 1st I though maybe a CPU heating issue. So I upgraded to a Zalman from the stock and that has helped out a lot but didn't solve my problem. I've have also thought about the North Bridge getting to hot but isn't appearing that way eather as based on temp of the heatsync its only getting to around 30c-40c. I have also investigated the GPU's but its not appearing horrible with temps at 80c-85c under load.

So I'm asking if anyone see something that i'm missing or just getting wrong. Here are the specs and temps(All under load):

Intel i7 Quad (50c-55c)
2 BFG Nvidia GTX 285 in SLI (80c-85c)
Kingston Hyper X 12 GB Ram w/ heatsync's
Silver Stone 750w PSU
3 Western Digital 1TB SATA 3 drives
Gigabyte X58A-UD7 MB

Note: The North Bridge may be a little hotter then what I have stated. As that is based on an in case temp. Compared to the 1 on the CPU Heatsync its about 20c less then actual temp. ie CPU reads 50c and case says its 30c

 

[dmcfc]

I'm not sure, but I think it might be your psu that doesn't have enough power to power that rig while gaming or anything that requires more power. That psu for sure power that rig with a 285 gtx, so I think you should try removing one of the gtx 285 and try to play a game and see if it shuts down, if it doesn't probably you just don't have a good enough psu, in that case you probably would need buy something more powerful. Looking at nvidia's website basically the only certified psu's to power 2x 285 are 1000w, a corsair 850w would probably do, but it's not certified, and the corsair 1000w is.

http://www.slizone.com/object/slizone_build_psu.html

also try using a power supply calculator

http://extreme.outervision.com/psucalculatorlite.jsp

 

[nerdynick]

The PSU was what I was thinking next. Just happy to see someone else came to the same conclusion.

 

[dmcfc]

try doing what i said, removing one of the 285's, and if doesn't power down you'll need to buy a new, better PSU. Just to be sure this time around take a look at nvidia's website for certified psu, even though a lot of not certified psu's would do.

if you can afford it go for a corsair 1000w!Really good psu, will power even two 5970!It's a quality psu, and will last a LONG time without having to upgrade PSU.