Hello!
I have 2 R9 280X and a R9 290 in my rig. The 290 is hashing like a camp! But both 280X are hash horrible with 500-600 khash/s each.
The thing is, that with a diffenrent system on another harddrive they are hashing okay (~670-700).
I'm using the same cgminer, the same hardware, the same drivers, the same os and the same settings but i get different results. I can't just use the better system because that is my desktop system.

I'm using a Powercolor and a Sapphire.
OS: Win 7 Ultimate with 4 GB Ram
MB: ASrock 990 Extreme3
Driver: Catalyst 13.12 (Beta did the same thing)

MSI Afterburner settings:
GPU Powertune: 20
Core Clock: 1000
Mem Clock: 1400(1500 didn't change much)

My CGminer settings:

Changing these settings didn't seem to do much, it rather seems random, sometimes ill get 100 less somthimes ill get 100 more -.-


Spotting any mistakes i could have made would be very appreciated