Thank you for the fast response!
It seems to be about a quarter of an inch of clearance between the PSU plug and the top/left part of the back plate. I'm no stranger to case modding and I'll snip it out by hand if I really have to. HP seems has a thing for having to use the jaws of life to take their cases apart.
This is the back of the case, if it helps in figuring it outhttp://img237.imageshack.us/my.php?image=hpim0381fp4.jpg