Quote from: ATCkit on June 23, 2016, 02:37:30 AM

Quote from: E on June 22, 2016, 08:55:58 PM

I don't want to take this too far

Quote from: philipma1957 on June 22, 2016, 08:38:08 PM

Quote from: Herv12 on June 22, 2016, 04:45:42 PM

Hello,

Technically, if the S9 really use 1275W At the wall, it's use 1275 x 0.93 = 1185W on 12V. So a good quality 1200W PSU is enough but be the smallest unit you can use.

But usually, best efficiency is obtain at the half of power. At full power, you usually loose between 1 and 2% efficiency.

So a gold PSU used at 50% is very near a platinum PSU used at 100% (and will probably be more reliable)

it says 1275 dc + 7% at wall based on a plat psu. that 1200 watt can do 1320 watts at the wall as I think it is a gold not a plat.

a 1275 dc x 1.1 = 1402 at the wall.

so you need a better psu then those 1200 watt hp dps 1200 and remember the spec up are for the batch 2 and batch 3 s-9's

the s-9 batch 1 was specced to run at freq 650 and use 1390 watts dc +7% if a plat psu.

there is no way the hp dps1200 should be used on an s-9 unless you really clock low like 450 to 500 or so.

I've finally managed to take some direct measurements of DC draw on an S9.
Even though it's mining on kano.is during the measurements, I don't want to go too far o/t with details, but:

The DC draw for this unit is 1.89W*MHz + 57W for fans/controller everywhere from 450MHz to 668.75MHz.

At 650 w/ 100% fan the DC draw is 106.67A @ 12.051V = 1285.5W
50% fan only saves about 10W, but does take the unit exactly to its spec of 1275W.

at 1500 watts for $119, this might be a decent PSU:

http://www.centrix-intl.com/details.asp?Parent2ID=1&productid=13323

firetreeactual might know more about this PSU?

Just saw this post...I haven't used this particular one, but I would trust it. I've been buying the 1KW HP bricks from Centrix for months, and they've been dependable and cost effective. If they say it's for an S9, it means they've tried it. They run a farm in WA as well. Price is sure OK. I don't have 240 available here, which is another reason why I use the 1KW bricks at 120.