I also highly recommend Kalroth's version of cgminer! The xIntensity feature allowed me use 2 threads with my 7950, getting it to hash on par with my 7970!
http://k-dev.net/cgminer/You're getting over 700KH/s from a 7950?

Been running all night at 669KH/s, so close!
I'm using 4 as XIntensity (not the normal -I) and two threads with -g
Nice, the 7950's are cheaper than many of the other options.
Does anyone know if the 7950's use more/less power than the R9 280's?
The R9 280's were kings in terms of price/hashrate/power usage but I am wondering if the 7950's with sgminer can beat them...
Thanks in advance.
I can tell you that my Gigabyte 280x gets a steady 730Kh/s and I have it undervolted to 1.075 and it stays around 73C, but I also bought mine for $300