Quote from: bazarimajom on December 28, 2013, 05:03:32 PM

Hello!

I'd suggest trying playing with different switches in cgminer. I have 2 280xs which are basically 7970s. Here is what you should try: --gpu-engine 1098,1084 --gpu-memclock 1500,1500 --thread-concurrency 11200 -I 13. First i set gpu-memclock to 1500 which helped me to get above 600 then, thread concurrency, then set gpu-engine clock and try a few values between 1050-1100, and wait a few seconds for the hashrate to stablize. Hope this help, i don't think flashing new bios will help. Also try it on a fresh windows, it helped me a lot too.

Thanks, but I systematically went over a lot of combination of switches, cgminer versions, driver versions, SDK versions.
I tried it on linux just to be doubly sure.

On the other hand it's been confirmed that XFX and some other cards have mining crippled firmware.
Some folks can flash their cards and get normal hashrates ~700-750kh/s.
I'm just unlucky as this is a non-ref design.