I have a R9 270x, windows 8.1, cgminer 3.1.1. The highest I can get is 330 Khash, I’ve tried a lot of settings, the most stable so far was: --thread-concurrency 8192 -intensity 13 --auto-fan --auto-gpu. Anytime I got above I 13 or above 8192 I get tons of errors without adjusting lookup-gap. I was hoping for about 450 or so but can’t get there so far.

Hello Phil,
I too just got started, I’m in Houston, I have one R9 270x so I started with that before I invest anything more. I’m getting about 330 Khash, thought I’d get about 450 but guess not. It would be interesting to see what you get out of your 2 x R9 280x, I was thinking of a 3 x 280 rig.