no, gq is longer* I believe.
I upgraded mine from 500b to 850w gq, and noticed the psu was a bit longer.
just take a rule and see if your psu has the space for 7" plus room for the modular cables.
600b:3.35" x 5.91" x 5.51"
850gq:3.35" x 5.91" x 7.00"