Something is overheating, Help Please

I Just got my new computer built, but something is overheating. I know that it isn't my cpu cause I just got a new cooler when i found out that it was overheating.

What happens is this, When i play a game it will after a certain time shut down, no beeps, no screens it will just shut down. I know that it is overheating because it will not shut down if my Window is open and it is cool outside(~15 degrees C or lower) and i don't think that it is a software related issue as i don't see how a software related issue can be fixed by cooling the computer.

Like i said before i got a new cooler for my CPU its the Corsair Cooling Hydro Series H5O. I also got a program for my graphics card that allows me to Change the fan speed on my Graphics card. I put the fan speed up to 100% and it doesent seem to change the issue. I also have a program that came with my Motherboard(Probe 2) that tells me the Temperature and voltage of my CPU and Motherboard(MB) and my cpu is at 35 right now and my MB is at 40 now. I dont know what the Temp is when it shuts down as It only happens when im in a game.

Now my Question is this, Is this my Chipset? or is it something else?

My system specs are:
Asus M4N82 Deluxe Motherboard.
AMD Phenom II X3 CPU
Nvidea Geforce GTX 275
Windows 7 32 bit
3 GB of Ram

Please Help me out here I really want to fix this before i cause permanent damage to my computer

Hi dude, Im assuming you mounted the motherboard onto the little brass stand-offs on your case and have used new thermal paste when you put the new cpu cooler on? daft things like that can often catch us out hehe, other thanthat post your build details to give us a better idea of what were dealing with will check back.

i used new thermal paste for my cpu and yes i did mount my MB on the brass stand-offs.
my gpu runs when idle and without fan increased at about 55 with fan increased at about 46 degrees, and it would be difficult to change the cooler on my gpu as its built in
what else do you want to know about my build?

it only happens when im running a game, as fir GPU-z ive never used it but sure ill try.
and PSU
Techsolo Black Mamba STP-650 640W

well after running GPU-z it seems that my graphics is the one that is overheating as it will reach very high temps of bout 69-70 before shutting down. So is it possible to change the cooler on my Geforce GTX 275?

At the present time my comp is on my desk with the side panels open, and the only thing that i notice about the PSU fan is that it makes a very high pitched noise.

alright the voltages are:
VCORE is 1.312 V
3.3 V is 3.408 V
5 V is 5.026 V
12 V is 12.416 V

To me they seem ok but im not a computer expert.

Ok thanks i am going to make sure by putting one PSU on the GPU and another on everything else. Ill then be getting a new PSU
Thanks for your help i was getting ready to first get a chipset cooler and then find out a way to cool the GPU before i would consider the PSU so thanks alot you probably saved me quite a bit of money