With 3 290s I'm getting just shy of 1600h/s with 1200/1500. I guess this miner is not pushing the cards so much in its current state as I can't get anywhere near this high of an overclock usually.
Are you running 290's or 290x? I can't get mine stable at those clocks, driver crashes and system locks up. I'm running mine at 1100/1300 and getting 450h/s
Running 290s, I'm using Stilt bios with an extra 38mv and powertune at 20. My cards are watercooled but they are running even cooler than x11 so I'm sure they would be fine on air as well.
I'm running sapphire 290 tri-x cards so can't use stilts bios on my cards
I'll have a bit more play and see if I can squeeze anything more out of mine.I've noticed on gpuz that the memory clock drops right down, does XMR mining use the cards memory much or is it like keccak and uses very little?
Raising mem-clocks from 1600Mhz to 1800Mhz resulted in an 8% hashrate increase for my rig (3x 280x Toxic). 1000 h/s --> 1080 h/s. (1100;1600 ---> 1100;1800)
To me it looks like performance moves proportionally to changes in clocks.
Doing 1103 h/s now with 1140; 1800. Been running stable for 6h+