One of my cards has me puzzled. It's a 7950 on a 7970 PCB (Sapphire OC). I can mine 1150 core at 0.94V actual and memory goes to 1700+ no problem but I can't get the expected hashrate out of it.
I have no such problems with my 7970s...3 different brands all performing as expected (750kh at 1088/1875, 720 at 1015/1750 and one 660 at 956/1650)
The 7950 is sharing a mainboard with a 7970 but I've tried singling the card out with settings but it just won't do top hash rates. At 1150/1640 it manages about 580 kh/s but I've clocked it down slightly to 1130/1620 since the temps went up. Gives me 565 ish. I've tried lower clocks (for memory especially) any number I could think of but I don't get anywhere near as good as I've seen some people do. I'm using cgminer (latest and previous) with 8192 concurrency g2 i13. Higher concurrencies did not gain anything, most of them lost quite a bit.
Anyone have one of these particular cards with better results?
From my testing I've found that 7970s do better with a core/memory ratio of 0.57575757.. and with the following settings:
--thread-concurrency 8192 -I 13 -w 256 -g 2
With 7950s, they just require a high core and memory clock and the following settings:
--thread-concurrency 21000 -I 19 -w 256 -g 1
I couldn't find any conclusive patterns regarding a special core/memory ratio that yielded the best Kh/s. My two 7950s are clocked at 1100/1600 @ 1.024v and get about 635 Kh/s each.
Since you're mining with a combination of the two, try running two instances of CGMiner. Use
-d 0 -d 1 -d 2.... to mark the cards you want to mine on.
