Proudly upgraded my 2x 6990 / Windows to a 3x 6990 / Debian. :-)
Now I get a weird situation: I am getting the same performance as with ONE 6990. :-(
This is catalyst 11.7, SDK 2.4 on a fresh Debian. clinfo, atconfig and flrxinfo see all 6 GPUs. Phoenix / poclbm see all 6 devices. I started 6 miners for 6 different pool workers and I get...a hash rate of 590 MH/s.
All 3 cards get warm, atitweak reports that all 6 GPUs are working, albeit at a utilization of 30%. If I start additional miners, situation stays the same.
When I start the miners, the first two miners run at 300 MH/s and on 2 GPUs. Adding miners (to the remaining 4 free GPUs) has them run slower and slower, evenly distributing the load on all 6 GPUs but never reaching more performance than I usually get on one 6990 card.
It's probably not the motherboard or the CPU, since on Windows the TWO 6990 nicely produced 1,2 GH/s.
After 1 day tweaking and twisting ... I am a bit desperate ... and could use some help ... please ...