Which PSU to get

[BNCID]

Adding a 3rd gtx 580 to my rig and im fairly certain my 850w Corsair PSU wont be enough. So im looking at 2 power supplies and not sure which would be better as they both get great reviews. Im looking at the Seasonic x-1240 and the Corsair AX1200i
http://www.amazon.com/Seasonic-SS-1250XM-X-Series-Power-Supply/dp/B00607JLWU/ref=sr_1_1?ie=UTF8&qid=1359495243&sr=8-1&keywords=x-1250
http://www.amazon.com/gp/product/B008Q7HUR0/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=ATVPDKIKX0DER
My specs are
i7 3820 @ 4.7Ghz
Asus Rampage Formula IV
16Gb(4x4) GSkill ripjaws DDR3 1600
Samsung 840 pro 256GB
WD Green 2TB
2x EVGA GTX 580 SC
Corsair 850TX
Im getting the 3rd card pretty much for free, as for budget I dont want to go over $280.

 

[djangoringo]

A good psu with 1200W is enough, both psus above are of high quality, i'd get the seasonic x-1250, it has more juice and it's cheaper, quality is the same.
There's also the XFX 1250W PRO1250W Black Edition, which is made by seasonic for less : http://us.ncix.com/products/?sku=65627&vpn=P11250BEFX&manufacture=XFX&promoid=1270

 

[BNCID]

Best answer selected by BNCID.

 

[BNCID]

Thanks