Ben_75 :
Suztera :
You don't have enough 6+2 pin pcie cables with that psu.
The R9 290 tri-x requires two 8 pin. Your psu only has one 6 pin and one 6+2 pin pcie cable.
and 280x or gtx960?
Depends which R9 280X. Any R9 280X that require two 8 pin, your psu can't support that.