2 Questions, Hashrate fluctualting & 3 @ R9 280X OC's on 1000W PSU

[Shenrox]

Hi Guys,

Iv'e got 2 questions.

FIRST: Does anybody know why the pool where i'm mining shows heavy fluctuations in my hashrate. CGminer shows a stable 710-715 Kh/s, but on the pool it will show as low as 550 and as high as 950??!?!

SECOND: I have a Gigabyte GA-X58A-UD3R motherboard with a 1000W Aerocool V12XT PSU, how do I calculate whether my PSU can supply enough power for 3 @ Gigabyte R9 280X OC's.
The PSU has enough dedicated cables coming out of it for 3 cards. I.O.W. 3 @ 6 Pin & 3 @ 8 Pin.
Also the cards will be undervolted to 1.075V. I'm getting a second one soon but am planning on adding a third.

Thanks a mil

[SheepOnDrugs]

You shouldn't care about what the pools says. The WU number in your cgminer is your actual mining rate which gets accepted by the pool and this one is right.

Can't help you with the second question though