my 6 280x card rig consumes like 550watt on x11 and i get about 2.08 MH per card running at 1040ish/1500
So i think its better to undervolt, and have less mh per card.
Did you use power meter to measure the power consumption?
I have 8 GPU rig with combination of 7970/7990. The power consumption is 730W. Total hash = 13.5MH/s.
core/memory= 850/1000MHz. VCore = 0.94V.
yeah i used a power meter. scrypt i get about 1250watt. and x11 its somewhere in the range of 550-600.
not sure about the 7990 tho. do you cound it as 2 gpus in your rig? but still 730watt for 8 cards isnt bad at all.
1X7990 = 2GPU.
What are your voltage settings and other configurations?
You are using higher clocks, so higher voltage. Therefore should be less efficient, but
Your efficiency: 2080*5/550 = 22.7 kH/s/W
My efficiency: 13500/730 = 18.4 kH/s/W
all my cards have been flashed to precisly 0.943volts since MSI are retarded and only allows 0.943v or 1.2v on the cards i got with serial starting with sb38
then i add +0.1v through msi after burner to get about 1.043 (althou afterburner reports 0.995)
and running at 1040/1500 (some cards manage 1060, some 1080) and mem is always 1500. i get about 2.08MH per card.
other config is the cfg setting in the main post.
i have also deactived everything possible in bios, and im using a 30gig ssd disk, low voltage ram with further voltage drop to about 1.2volt, running at 800mhz. undervolted cpu as well but its mostly idle it doesnt matter that much tho.
