Quote from: Ayers on March 04, 2016, 03:06:03 PM

Quote from: Fademigo on March 04, 2016, 01:58:47 PM

Quote from: Ayers on March 04, 2016, 08:20:26 AM

Quote from: Bostonias on March 04, 2016, 07:58:30 AM

Quote from: bluebox on March 02, 2016, 09:20:45 PM

Much of the original point I tried to make has evaporated in light of ETH >.015BTC (.017? .019!?! .02!!!), electric costs should be a non-consideration for most. That said:

Quote from: Mastsetad on March 02, 2016, 01:18:43 PM

But that extract fan power consumption is due to the mining as well. So we have to take that in to account.

100% GPU TDP on 970 = 145W

Do the math, break it down, here's the numbers:

Overclocked, maintaining <70C core temp (high fan profile):
gpu1 (incl. fans on card): 108W (75%TDP)
gpu2 (incl. fans on card): 115W (80%TDP)
4 case and 2 cpu fans, hdd, mobo/cpu: 50W (case fans ramped to 60%)
Total so far: 273W
PSU loss: 55W (80% efficiency; 0.2 * 273 = 55W)
273+55 = 328W, or basically what I've monitored on the UPS
42MH/s, 7.8W/MH (total system), 5.3W/MH (gpus only)

Stock, maintaining 75C core temps, stock fan profile, both @65%TDP:
gpu1: 90W
gpu2: 90W
case fans+hdd+mobo+cpu: 30W (silent pc mode)
Total so far: 210W
PSU loss: 42W
Total system: 264W
36MH/s, 7.0W/MH (total system), 5.2W/MH (gpus only)

Something I'm going to try is disabling Windows Aero. Even though it's a headless system and it's not doing anything, some have mentioned it stealing GPU power all the time regardless of use, therefore decreasing hash. I've seen weirder things, especially on Winblows. God, I've got to roll Mint or something.

I've seen the "my 280x will do xxMH on yyyW with zzzV undervolt" before, I still have no clear idea because so many things play a factor in pushing the limit. I've seen people today who own multiple rigs, running mixes of 7950 and 280x, undervolted/clocked/tweaked/whatever, drawing over 3KW to get 350MH/s (9W/MH!), and they're happy with that. To each their own, ETH's at .02BTC, electric ain't much of a matter no mo.

I think I'm done with this particular thread. Grin

I have 4x7990 undervoltaged to 0.95 V, 850/1250MHz. It does 156MH/s with 1320W from the wall, So that is 8.46W/MH/s.

you can do better with six 970 = 1020w for 132 megahash, this is 7.7w/mh, and this is also a more cheaper rig

4x7990 = £1100. 6x970 = £1500. So it is more expensive to use the 970. Maybe the 970 will hold value better.

you're probably comparing used card versus new, there is no way that you can buy a 7990 for that cheap if it is new

The £1100 for 4 will be the second hand price. The new ones cost £600 each when they first came out.