More details here:
http://www.tomshardware.com/reviews/...mark,3382.html
It is compared to the HD7670M.Both cards have GDDR5 with the HD8790M having 384 GCN shaders and the HD7670M having 480 VLIW5 shaders. The HD7670M is basically the mobile version of the desktop HD6670 GDDR5.
Edit!!
It seems TR got a sample too and compared it against the HD7690M GDDR5:
http://techreport.com/review/24086/a...adeon-hd-8790m