Hi,
bitcoin miner setup or not, the temp is just about to high.
Now, how to solve this?
First: Intel I7 - 920 should be fine as long its temp is below 70degr C
But I dont' expect the cores will be used at all and therefore the CPU case temp will be very low.
Second: Your xfx 280x black double dissipation edition (3gb)
will require less than 175W
So in total Your whole rig or computer will not in any way consume more than 225W
A 400W Power supply will do just fine, and even that is a little bit overdue.
Now, Yore are saying that the graphics card is overheated?
Well get a better chassis unless you have cruiser problems?
You need a better air flow through the chassis.
Best regards from Sweden