OK I'm jobless, bored out of my mind and need something to do. Obviously I won't be buying any hardware... But I can dream can't I? hahaha None-the-less I can play with the hardware & ampermeter I've already got.
Anyway I want to build (more like dream for now) a cluster of machines that gets proportionately the highest Mhashs for as few watts as possible. I also would like to get it powered by a solar array (I've always wanted to get one started...). Initial cost isn't such a big deal, but obviously cheaper is better.
For now I want to discuss minimizing energy consumption. I know underclocking and undervolting the VRAM of the GPU is one thing people do. But here's a few thoughts... Why not undervolt and underclock the NB of the mobo? Disable all unused integrated components? Going diskless (using boot server)? Under clock/volt the CPU and disable all unused cores? Using DC directly (assuming a solar array or other DC source)?
I have no clue how much energy would be saved by under clocking/vloting the NB. I guess that's what my ampermeter is for!
Assuming the board actually cuts power to integrated devices, it should be obvious why you'd wanna disable as much as you can. (I guess the ampermeter is good here too for verifying if integrated devices are actually powered off)
...If you boot using linux without a GUI you could get more Mhashs out of the GPU. When I set windows to performance mode I got another 7ish Mhashs out of mine. Imagine what Linux could do with no GUI at all!
Using a boot server, you can lose the HDD. Which will cut-out about $60 (average price on newegg for cheapest HDD... unless you want refurb IDE) and use about 7-15 watts less per machine. For the boot server I was thinking Raspberry Pi, because it's only $35 and uses 3.5 watts (according to wikipedia). Going diskless also means disabling IDE/SATA controllers.
Since mining on the GPU has very little to do with CPU, you could possibly get away with the cheapest CPU and configure it to consume as little energy as possible.
Using DC directly (from batteries--no inverters), you could ditch the inefficiencies of PSUs--and even the PSU all together. This would shave off cost of PSU, waste less energy and be one less thing to break down.
....Don't forget, every watt shaved-off is 1 less watt your AC needs to absorb!
What you all think about my ideas so far? I had a ton more ideas but I can't think of them for now. I'll post them as I remember and I'll comback with the results of testing with my ampermeter.