Games keep crashing but the PC doesn't, PSU issue?

[nico53laval]

First of all, my rig : Gigabyte GTX 670 @ 136x MHz core, i5-3570K @ 4.3 GHz, Asrock Z77 Pro3, Asus Xonar DX,Corsair Carbide 400R with the 3 stock fans, Cooler Master Hyper 412S with one fan, a few USB devices, Seagate Green 7200rpm HDD, Samsung 830 128GB SSD.
My PSU : Antec Earthwatts 500W 80+ Bronze
I experience very annoying PSU coil whine in all my games, but that's not my main issue. A lot of them crash after a few minutes or a few hours, even the ones that shouldn' t require that much power (Dirt 3...), but my PC doesn't, and I wonder if the issue is a lack of PSU power or not. I don't really have the money to get a new PSU right now and I can't RMA it anymore since I've bought it over 2 years ago.
Thanks for your help.

 

[Z1NONLY]

What video card were you using with your PSU before you got the 670, and did it crash on games with the other card?

 

[nico53laval]

An HD 5850 with a Phenom II *4 965 BE without sound card nor SSD, I don't think the new rig uses a lot more power right? I think some games crashed too, but not as often.