The mailman brought my brand new Radeon HD 7970 today and of course one of the first things that I wanted to try with it was to see how well it can mine
![Smiley](https://bitcointalk.org/Smileys/default/smiley.gif)
I've noticed that there's an almost complete lack of benchmarks for this card on the web (the only one I've seen has been the 414MH/s result from tom's hardware) so I've created an account to share my results here.
I'm using cgminer-2.1.1-win32 as my mining software and figured that this would be a plug-and-play deal, but I ran into a couple of initial snags. The first thing I noticed is that the card would report that it was hashing but would never get any accepted results. I was unable to get the phatk kernel working, however I found that by using the "--kernel poclbm" option and editing line 36 of poclbm110817.cl the following way to disable BFI_INT that I would start getting accepted hashes:
With those two changes to the default configuration of cgminer hashes start to get accepted, but the 290MH/s hashing performance with the default settings (-g 2 -v 2 -w 128) for this kernel were slower than the 310MH/s from the trusty OC'd HD5850 that this new card replaced, so I played around with the --gpu-threads, --vectors and --worksize settings and here's a small table with the results:
--gpu-threads 1 --vectors 1 --worksize 32 : 224MH/s
--gpu-threads 1 --vectors 1 --worksize 64 : 448MH/s
--gpu-threads 1 --vectors 1 --worksize 128 : 446MH/s
--gpu-threads 1 --vectors 1 --worksize 256 : 448MH/s
--gpu-threads 1 --vectors 2 --worksize 32 : 141MH/s
--gpu-threads 1 --vectors 2 --worksize 64 : 285MH/s
--gpu-threads 1 --vectors 2 --worksize 128 : 283MH/s
--gpu-threads 1 --vectors 2 --worksize 256 : 284MH/s
--gpu-threads 1 --vectors 4 --worksize 32 : 66MH/s
--gpu-threads 1 --vectors 4 --worksize 64 : 133MH/s
--gpu-threads 1 --vectors 4 --worksize 128 : 133MH/s
--gpu-threads 1 --vectors 4 --worksize 256 : 133MH/s
(Note: all of these results were using the standard 925MHz core and 1375Mhz mem clocks)
Given these results I figured that -v 1 -w 64 was probably the best kernel setting so I tweaked the number of threads:
--gpu-threads 1 --vectors 1 --worksize 64 : 448MH/s
--gpu-threads 2 --vectors 1 --worksize 64 : 467MH/s
--gpu-threads 3 --vectors 1 --worksize 64 : 474MH/s
--gpu-threads 4 --vectors 1 --worksize 64 : 472MH/s
--gpu-threads 5 --vectors 1 --worksize 64 : 473MH/s
.
. (No apparent trend so I skipped these...)
.
--gpu-threads 8 --vectors 1 --worksize 64 : 473MH/s
So the best settings I could come up with for the day were -g 3 -v 1 -w 64 giving a hashing rate of 474MH/s! Not too shabby considering the card is using stock speeds! And its roughly a 15% higher hashrate than what was reported at tom's.
I'll continue experimenting with other settings over the next few days, but this initial testing makes me wonder what a kernel rewritten specifically for GCN (using the 16-wide SIMD, among other things) could do.
**** UPDATE ****
Someone suggested that I give a recent version of the DiabloMiner a try since it should have decent support for GCN, so I did.
~650MH/s with the default diablominer settings and the card OC'd @ 1125/975MHz:
https://i.imgur.com/f8NnZ.jpg~530MH/s at standard clocks:
https://i.imgur.com/DeUxm.jpg