Gigabite GV-R928XOC-3GD R9 280X rev2 with latest Catalyst drivers (13.251) and default settings: 20 hpm

I've previously used a different driver version with cgminter and got quite a bit more out of it with some clock tweaking, I suspect 25 hpm is possible. I'll repost if I confirm.

Thanks so much to the creator - when I've got some confirmed coins I'll send you a tip.