would a 850w power supply be enough to have to r9 290x in crossfire?

[Banko]

so i was thinking if buying another r9 290x. but i have a 850w msmart thermal take psu would that power supply beable to run 2 r9 290x's?

 

[Suztera]

Ideally you want a decent 1000W psu sucha s the EVGA G2 1000W.

 

[17seconds]

Here is Guru3D's power supply recommendation:

AMD Radeon R9 290X - On your average system the card requires you to have a 550~600 Watt power supply unit.
AMD Radeon R9 290X Crossfire - On your average system the cards require you to have a 800 Watt power supply unit as minimum.
If you are going to overclock GPU or processor, then we do recommend you purchase something with some more stamina.
http://www.guru3d.com/articles_pages/radeon_r9_290x_crossfire_vs_sli_review_benchmarks,4.html