Sorry, just sounded like you were trying to say that the difference was caused between the kill-a-watt measuring AC power which is different from DC power. Some of the cheaper power supplies use the input power rating as opposed to output power rating as it makes them sound better. As for the PS in the OP's post, I've never really looked at it so I can't comment on which it uses, although I imagine the 850W rating would be output power.

A more accurate answer is that the Kill-A-Watt measures total input power for the system including PSU losses. The PSU spec (850W in this case) may be total DC power output, IE, before losses attributed to the PSU.

If you're reading 855W from the wall on a 80% efficient power supply, the total power delivered to the load would be approximately 684W. If it was a 90% efficient power supply and still drawing 855W then the total load power would be 769W.

A Watt is a Watt, AC or DC is irreverent until you start getting into power factor considerations and VARS

Any updates on compatibility with the AMD 7000 series CPU's and the R9's?

I'm currently running a mix of both but would be interested in this board to simplify setup.

Also, how is power controlled? I see that it does not have a 24pin atx connector located at the solder points on the board so it must pull all the power from the 6pin connectors, I'm wondering how power on/off is accomplished. Personally I'd like to have 2 or 3 24pin atx connectors, even if just to be able to control the power on/off of multiple PSU's without the need for extra adapters or splicing wires.

Got a few cards running in the same system. A 7870, 7970, 270X and a 390X. Another 7970 and a 280X are currently on the way and will be playing around with a GTX 960 tonight. Here's what I have so far but will (hopefully) editing the BIOS on the 7870 tonight. All cards are currently running on an ASUS P5B-Deluxe with a Pentium Dual-Core e5300 and 6GB of DDR2-800 ram on Windows 10. Using the latest AMD-Blockchain drivers.

GPU's MODEL NAME: Sapphire 7970 Dual-X
VRAM: 3GB GDDR5 (Hynix)
CORE CLOCK: 1075
MEMORY CLOCK: 1499 (6Ghz)
HASHRATE: 304.4 h/s
MINER SOFTWARE: Nicehash (Claymore Z-Cash Miner v12.6)
OS:
TDP(OPTIONAL):

GPU's MODEL NAME: Sapphire 7870
VRAM: 2GB GDDR5 (Elpida)
CORE CLOCK: 1150mhz
MEMORY CLOCK: 1250(5Ghz)
HASHRATE: 168 h/s
MINER SOFTWARE: Nicehash (Claymore Z-Cash Miner v12.6)
OS:
TDP(OPTIONAL):

GPU's MODEL NAME: XFX 390X
VRAM: 8GB GDDR5 (Elpida)
CORE CLOCK: 1125mhZ
MEMORY CLOCK:  1625MHz (6.5 Ghz)
HASHRATE: 423 h/s
MINER SOFTWARE: Nicehash (Claymore Z-Cash Miner v12.6)
OS:
TDP(OPTIONAL):

GPU's MODEL NAME: Sapphire R9 270X
VRAM: 2GB GDDR5 (Elpida)
CORE CLOCK: 1250Mhz
MEMORY CLOCK: 1500Mhz (6Ghz)
HASHRATE: 201 h/s
MINER SOFTWARE: Nicehash (Claymore Z-Cash Miner v12.6)
OS:
TDP(OPTIONAL):