CPU crashing

To be clear, are these "crashes" BSODs (BlueScreen Of Death) or just the game crashing, i.e. stops responding? Make sure you have all the latest drivers, e.g. chipset driver, gpu driver, and maybe a BIOS flash. If it still doesn't work you might want to try to get inte BIOS and check your values. Check the voltage on your CPU and memory modules. Your CPU at stock should work around 1.20V but if this value is too low, you might consider bumping it up a noch (very lightly) and vice versa, if this is too high, you could very well try to underclock.

The underclock would be an idea to try, underclocking is easier than overclocking though you don't have to compensate for anything. You basically adjust the voltage to the point where you feel that your system is stable, and adjust the cores' frequensies downwards.

i would probably blame the crappy PSU first and foremost.

depends on the type of crash though as Njure said.

maybe a heat issue.....

My bad for not clarifying. By crashes I meant my computer fully shuts down and restarts itself. Since it's a new ASUS motherboard, it comes with a firmware called express gate that loads prior to the windows 7 operating system. For more info: http://www.brighthub.com/computing/hardware/articles/30...

It restarts itselft everytime as I explained above. I'm suspecting the lack of power in the power supply, however, it should be more than enough since my computer parts should only require around 440W or so and the power supply is 530W. Forgot to mention this only happens when I'm gaming with MW2 or SC2. Normal usage of the comp is perfectly fine and I can run games like WC3 normally.

almost certainly the PSU then.

even though it claims to have enough watts, its a very low quality PSU. they are never to be trusted.

do you know someone with a PSU you could borrow to make sure that it is the cause of the problem?

once confirmed, i would recommend picking up a corsair PSU. a vx450 would be enough for the system, but a 550 will give you a little more headroom.