OH too cool and more hash rate
how much of voltage? and asus 280x series? (dc2t -i think this- / dc2t v2 / matrix / other)
my asus dc2t clock 1120 can do only 485h/s fan speed higher and temp heat more than you
ASUS Radeon R9 280, R9280-DC2T-3GD5 1150/1500/1093mV - 515h/s - 175W (215W rig)
I get ~535 h/s on the exact same card at 1190/1800 (watercooled).