check - 950W 80+
If you are probably pulling 85% of peak DC load that could be costing you a couple %. Most 80Plus-Gold PSU have a much flatter curve so the drop off isn't bad you might be burning 20W+ more here. Probably not worth a new PSU, just something to keep in mind. Also check the temp of your PSU. The "80Plus" program is good because it gives us something to compare models but it is somewhat unrealistic. They measure efficiency at 77F. Even if your room is 77F it is unlikely the inside of your PSU is 77F.
I would like to see a 90Plus program measured at 85F.
nuts...now I have to hook up a monitor and keyboard ;-) I'll do that later
Yeah it is the only time I hook up the keyboard and mouse. Turning off the junk in BIOS can save you 20W or more. Especially stuff like USB3, Floppy controller, onboard audio because they aren't part of the southbridge they are usually seperate ASICS. 5W here, 2W there, 1.5 here. It starts to add up.
Last thing I would say is I used MSI 890FXA-GD70 board. Different boards may have different system wattage depending on power configuration and components used.
I get 435MH/s at @950/300 - very stable. Are you running with cgminer? I'm using bamt, I haven't made the plunge yet (is it worth it?)
I actually used cgminer before BAMT. BAMT adding cgminer is why I started using it (after I and other paid to have RPC support added to cgminer). The learning curve is a little steep (just because cgminer has so many options) but once you got the config files set I think it is unbeatable.
Coincidentally I had ordered an OCZ 1250W 80+ PS last week and hooked it up to that same rig today, changing nothing else. Low and behold I dropped from 900W to 790W! After looking a bit longer, the 950W PS I was running is apparently not 80+ as I had thought, lesson #1.
I also pulled out the monitor/keyboard and turned off everything as you mentioned and dropped another 10W. A rough calculation puts that savings to be a little over $0.50/day with this power supply. Not too shabby.