small PSU's retired there?

i'm looking for a small form factor PSU that'll still give me ~500W. I have a personal installed within a medium-large guitar ampere, and it's not very deep. i dont own much in in that, just the motherboard affixed to the front surface. i hook an optical drive up only ...

Source: http://www.daniweb.com/hardware-and-software/pc-hardware/cases-fans-and-power-supplies/threads/288344/small-psus-out-there