Quote from: adam1111 on February 03, 2018, 11:16:14 PM

I would appreciate some PSU recomendations for setting up a 12 card build all GTX 1080 cards. I'm gonna need 2 PSU's The mobo I am buying is
ASUS B250 MINING EXPERT. Which has 3 spots on the mobo for PSU's so to pwer the mobo and six cards how many watt PSU?. And to to power just 6 more cards what size PSU? would a 1200w work for the 6+mobo and an 1000w for the additional 6 cards? Or can I get away with using smaller PSU's?Thanks.

You could get away using smaller PSUs if you bought 3 PSUs and did 4 cards per section of PCIe slots (perhaps 1x 1000W and 2x 850W PSUs, assuming you keep overclocking to a minimum, and your CPU is reasonable for a dedicated GPU-mining rig). However, this would make expanding your rig in the future more of a pain than if you purchased 2 higher-end PSUs, and left the third section free.

If you're always careful to run the cards below full TDP, then perhaps you can get away with predictions showing 90% use (with 1080s having a 180W TDP, this would be 1080W for 6 cards, placing a 1200W PSU at 90% of its rating*). I wouldn't personally recommend banking on your ability to keep your mining system from hitting the full TDP, but some people do it successfully.
*This did not include the nonnegligible draw from the CPU and other necessary components. 2x 1200W PSUs wouldn't be enough for a 24/7 rig pushing 12x 1080s at 100%.

If you want to play it safe and only use 2x ATX PSUs, try for 2x 1400-1500W. Generally, you want the sum of all TDPs for components connected to each PSU to be somewhere in the ballpark of 70%-80% of the rating, for safe 24/7 operation.