Damn. That's cramped.
BTW, your PSU may be cutting it pretty close with a GTX 285 and a core i7.
Regardless of the wattage, dual 12v rail PSUs aren't too good for power hungry systems like yours. Especially with only 19A per rail.
You should consider upgrading that before too long. You could run into problems later on... and there's a chance it could be related to your performance problems right now.