Sorry for another "Is it big enough" thread but.
I have one of the original Corsair HX520W PSUs (circa 2006) that I am rather fond of due to it's quietness but have my eye on a Gigabyte GTX670
that has a published
550W minimum requirement.
Have noticed that the max draw from these cards appears around the 200W mark in reviews & would be running with a 125W 955BE so it looks OK to me.