Lower CPU Clock, Hyper-threading, etc to save watts!

[kcobra]

This weekend I have been running two 5830 cards in my i7 930 rig that used to be used for gaming and folding. Needless to say it had a decent overclock (3.8ghz), hyper-threading enabled, etc. When the 5830's were running full bore my wattage, as measured by my Kill-A-Watt meter, was ~500w. So I decided to see what bumping down the CPU would save in watts. I turned the bus frequency down to 133mhz, chose the lowest multiplier my bios would allow (12x), turned off hyper-threading, bumped memory voltage back to normal, etc. After all of that my watt usage when mining is now ~430w!

I tried disabling 2 of the cores on the i7 also but when I did that post would not make it past the RAID detection for some reason.

I know all of this is pretty common sense but I was surprised how much wattage I saved. Hopefully this will benefit others like me who have re-purposed a higher end machine for BTC mining.

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[RyNinDaCleM]

When you lowered your CPU multi, did you lower your VCore too? This will lower heat quite a bit. You could probably get away with 1.1v! Also, if your RAM is underclocked, you could tighten the timings to something like 7-8-7-20! This will make the CPU underclock seem a little snappier!

[bcpokey]

You could have saved yourself as much or more heat/energy by locking the card affinity to a single core, and still had a usable computer.

[phelix]

My rig uses less than 50W on top of the cards and I did not even optimize cpu voltage and bus speeds and so on. it is a an AMD 240e

[kcobra]

When you lowered your CPU multi, did you lower your VCore too? This will lower heat quite a bit. You could probably get away with 1.1v! Also, if your RAM is underclocked, you could tighten the timings to something like 7-8-7-20! This will make the CPU underclock seem a little snappier!

Yep, dropped the VCore back to "Auto". I probably could tweak it below spec but I don't have the energy to find the lowest stable setting.

[kcobra]

You could have saved yourself as much or more heat/energy by locking the card affinity to a single core, and still had a usable computer.

While setting the process affinity to a single core definitely help, it does not lower my system wattage to the underclocked levels. When I went back to my overclocked settings and set both phoenix processes to one core the watt used by the system went down to ~465w.

With the underclocked cpu, putting an 80mm fan on the hotter video card and setting both phoenix processes to one core I am down to ~420w!

Note that the fan trick is another power saver. By lowering one of the cards down from ~75c to ~70c I am saving 5 watts.