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Topic: Dual VisionTek AMD 7990 low scrypt hashrate (SOLVED) (Read 695 times)

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I was getting pretty dismal hashrates on my dual 7990 rig, and I didn't find a solution out there so I thought I'd share my solution, hopefully this will help someone out:

Code:
bfgminer -o 127.0.0.1:7002 -u lolz -p wat --scrypt --intensity 13 --gpu-fan 100 --scan auto --thread-concurrency 2 --gpu-threads 2 --worksize 128 --gpu-engine 975 --gpu-memclock 975
Turn off crossfire too.  Same settings for cgminer.

Main surprises are lower thread concurrency, and thread concurrency and a modest worksize gave me better performance than the prescribed numbers.  I'm underclocking gpu and memory to keep heat down, I can reach 3Mhs with "--gpu-engine 1000 --gpu-memclock 1550" but with heat problems >95C. 

This got me to 2.66Mhs (scrypt) stable but hot ~90C.  Pretty exciting, since I was getting 900khs to 1.2Mhs and constantly overheating.  Planning on re-applying heat grease, and undervolting soon.
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