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Author Topic: Sapphire 7970 vapor-x GHz 3GB Hash rate  (Read 3354 times)
Xanthe
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June 05, 2013, 09:44:33 PM
 #21

hmm I cannot even change mem voltage on my sapphire ghz 7970, does any of you have the same problem?
I am getting like 300+ kh scrypt hash rate no matter what I do, this really sucks!

You will need to do a rather unsafe overclock on memory. I have core voltage at 1080 (default 1200) with the core clock set at 856 mhz (performance drop at 857 or higher). Then tuned the memory voltage between 1625 to 1630 (default 1500). When the memory is overvolted you can turn up the memory clock to 1775-1785 mhz. Be sure to run Intensity at 13 in cgminer. If you set any other intensity with these settings it drops 100 kh/s per gpu. I believe these ghz editon gpu's are going back to the store in my case as they are horrible for scrypt mining.
The speeds seems to be exactly same with 1333mhz, and 1600mhz RAM. Please PM me if you can find any settings that perform better. Hope this helps.

What software are you attempting to use to change the memory voltage? MSI Afterburner works for me with a Sapphire 7970 Dual-X. There will be a drop-down type arrow right next to the core voltage control that you can click on and it will reveal the memory voltage control.

As for your hash rate, try these settings in cgminer:
Code:
--intensity 13 --shaders 2048 --worksize 256 --thread-concurrency 8192 -g 2

That gets me ~690Kh/s @1019mhz core and 1496mhz memory (core voltage set to 1100mV, mem voltage 1500mV).
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