Try
24576 6144 for thread concurrency. Or 16384 or slightly below.
(Sorry i misread that you had problems with your 7970 not 7850 ^^)7xxx series cards
Use reaper or cgminer versions 2.11.3 and up (see update below). Set thread_concurrency to somewhere slightly below 64 * bus_width_of_card_in_bits. So, for a 7950, that would be 64 * 384 = 24576; ideal values are 21712 or 24000. Find your bus width here:
http://en.wikipedia.org/wiki/Southern_Islands_(GPU_family)
To find the optimum thread_concurrency for your card, you will need to search above and below this estimate ideal value and see what is fastest.
https://bitcointalk.org/index.php?topic=117221.0Also try without shaders, the miner should recognize the optimal number by itself. And I'd set intensity to 18-20 when you're not using the desktop. At least set it to this on the secondary card not used for the desktop.
And i'd try guiminer's standard settings for the gpu, they should give good results.
Maybe some clues for you.
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