Quote from: xorpheus on February 21, 2014, 07:51:46 AM

Quote from: eduffield on February 21, 2014, 02:20:24 AM

I was thinking about this earlier, does anyone know how hot GPUs run mining bitcoin? If that runs cooler I would tend to think the extra power draw and heat is because scrypt pretty much rewrites the entire ram available as fast as possible over and over again, whereas Bitcoin/Darkcoin would only use a small amount of ram.

Curiosity got the better of me... below are some test results for 2 x HD7950. Power is measured at the wall. Idle power is 210W.

darkcoin
hashrate: 3.80Mh/s
temps: 52,57
power: 415W

bitcoin
hashrate: 1.21 Gh/s
temps: 69,76
power: 680W

litecoin
hashrate: 1.34Mh/s
temps: 73,81
power: 740W

This may not be a valid comparison because I don't know how to optimize settings for bitcoin. All I did was fiddle with the intensity setting. Does 605Mh/s for each HD7950 sound reasonable?

Thank-you for the testing and for sharing your results.

I'm seeing almost the exact same hash rate from my 7950s while mining DRK, and while anecdotally I know they're running way cooler, I don't have a Kill-A-Watt to test the power draw. Taking your idle draw into account, it seems that each 7950 draws roughly 100W extra mining DRK versus 265W mining LTC. Saving 165W per card shaves an awful lot off the electric bill when they're going full throttle 24/7