I'm fairly new to mining and have ordered a number of 5xxx and 6xxx cards to get started. So far I have received (2) 5830's and (1) 6850 and have had a chance to play around with them. I have an older AMD Socket 939 board that supports SLI so I can't run any cards in crossfire but I have been able to install all 3 cards successfully...
The motherboard is an older ASUS A8N32-SLI with (2) x16 PCIe slots, they are PCIe 1.0 slots but I'm told this shouldn't matter. The 6850 installed without a problem running SDK 2.4, Phoenix 1.5.2, and the Phatk2 kernel. When I tried to install the 5830's however, the system would not boot which I later found to be a problem with PCIe 2.1 compatibility with 1.x slots but was able to successfully install one of them if I installed it in the 2nd slot...
As for speeds with only a single card, I was able to get the following:
6850 (970 core / 300 memory): 269Mh/s
5830 (980 core / 300 memory): 314Mh/s
5830 (1000 core / 300 memory): 323Mh/s
I'm pretty new at this, however I think these numbers look about right so far...
Now, the problem comes in when I install the 6850 in the first slot and either 5830 in the second slot. If I try to run the monitor on the 5830 I get a bunch of white/black lines on the screen, so I put the monitor on the 6850. I manually adjusted the clock speeds for each card using afterburner and created a separate batch file for each card using (DEVICE=0 and DEVICE=1)
The 6850 is able to maintain speeds between 230-259Mh/s (still slower than the original 269) but the 5830 jumps all over the place ranging from 190-280Mh/s
If I stop either one of the miners, the speed of the other goes back to where it should be (269/323)!?
The only thing I noticed is different is if I open afterburner... The GPU usage fluctuates between 60-99% on both GPU's (more so on the 5830) and mirror each other. For example while Card1 is at 99% - Card2 goes down to 60%, when Card2 goes back up to 99% - Card1 goes down to 60% or so...
Can anyone please tell me what is wrong!? I should also note that CPU usage is also very high but not more than 70% on each core. Are the 32 PCIe 1.0 slots not enough? CPU not strong enough? Or something else entirely??
Flags for each miner are set at:
-k phatk DEVICE=0 WORKSIZE=256 VECTORS BFI_INT AGGRESSION=11 FASTLOOP=false
I have also tried different aggression settings, nothing seems to change.