Vista - PC Crashing at game start

I'm currently using Windows Vista Ultimate x64 SP1 (Fully updated, specs below). After installing the drivers and such, I can start games and such, i.e. Counter-Strike. But soon after I join the game, without warning, my pc suddenly turns off. I believe this may have something to do with my gfx card/power supply;

Here are my specs:
EVGA NVIDIA 280 GTX
650W Zephyr Power Supply
MSI P7N SLI Platinum
Intel Core 2 Duo 775 CPU
WD 750GB 7200 RPM
CoolerMaster Cosmos S Case
8GB OCZ DDR2 RAM

Although initially my power supply didn't have enough 8-prong plugs, I got suggestions for a new PS, although I have little to no suspicions about any possible hardware errors.
I'm almost positive that this isn't a software issue, being that I only received my pc yesterday... I've also tried closing nearly every process that could be interfering with my pc, and still nothing. I'm thinking this is a lack of power issue, but I have no real experience with anything power supply related.

Thank you for any help!

Received it yesterday from who?

It's custom, I bought it from a houston based company called directron and had them put it together

did someone build this for you..?

is the rig stock or have you OCed it...?

ahh...its custom built is it stock settings

here are your PSU specs....
According to HEC, both the +3.3V and +5V line can deliver a maximum of 24 Amps each for a total combined output of 140W. There are four +12V rails with 17 Amp ratings each for a combined power output of 576W.

& here is the recommended requirement for a GTX280
A GeForce GTX 280 requires you to have a 550 Watt power supply unit at minimum if you use it in a high-end system. That power supply needs to have (in total accumulated) at least 40 Amps available on the 12 volts rails.

now im not too sure about PSUs with multiple rails you may have enough but im sure someone will let us know..

What drivers did you have to install if it came pre-built? Please be as specific as possible. Do you have another game besides CS you can try?

You said you were worried that your PSU didn't have "enough" 8 pin PCI-E connectors, so how did you get around this; what was your "fix"? Is there anything else you had to install or set up yourself?

There are a couple things you should run to see where you stand: Orthos - Overclock.net - Overclocking.net dl and run Orthos. Let us know when the test fails, if it does. If it's cpu or memory related, this will tell you. If it's graphics, then another game should tell us.

btw, right click Computer and select Properties. Under Tasks on the top left, select Advanced System Settings. Under the Startup and Recovery menu click settings. Under system failure un-check Automatically restart. Save your changes and exit out. Have pen an paper handy so you can write down the exact error messages that flash you the next time the machine has a problem... then go re-create that problem... load up CS.

Nono, they just put the parts together, I installed Windows.
I installed the motherboard drivers, sound card, and gfx card drivers.
I also installed all the updates for Vista SP1.
As for my 'fix', I bought a new PSU.
And I've run it against World of Warcraft, WC3, CS 1.6, and TF2.

OK, your initial post is a little confusing, so bear with me. Is the PSU you've listed the one currently in the machine or the one it came with? Does it have two 8 pin PCI-E connectors for the graphics card?

Do all the games you've listed shut the machine down or just CS? Have you run CS again to recreate the error? If not, do so and write down the error message.

The PSU I'm using right now is NOT the one that I originally used, but now it has the sufficient amount of PCI-E connectors.
All the games I've tried crash my PC, and none of them CREATE error messages, my PC just turns off without any error.

It certainly sounds like a bad PSU; although the chances of you getting two bad PSU's in a row are very slim. It's also unlikely that directron let a machine go out the door knowing it had an inadequate PSU; possible, but still unlikely.

Do you still have your old PSU? Does it have an adapter you can use in place of the second 8 pin PCI-E connector? I would try and hook up the original PSU with only the board, the boot drive and the video card. Make sure when using the adapter that the only thing on that lead is the graphics card... no other peripheral devices.

Temperature issues can cause those symptoms too. Check the system temperatures with HWMonitor.