I run my main desktop with a Q9550 and GTX260 on a 430W Seasonic S12II. I can be compiling and have a 3D game running in the background for hours and the I won't feel any heat on the PSU chassis or from the exhaust.
Apparently my graphics card recommends a minimum of 500W PSU and a 36A rating on 12V. PSU doesn't meet either of those specifications on top of needing to power a quad.
This might actually be a problem..
No problems at all, whatsoever.