loveGamer :
So for Mining purpose, Can you please confirm that the CrossFire and the PSU (http://pcpartpicker.com/part/seasonic-power-supply-x850) that I have mentioned in the parts should be good.
I see in reviews that overclocking this card draws more power like more than 450W. I believe that there wont be much power left with the listed PSU to output it if i OC these two cards for mining. In this case Wat would happen. Please advise.
For bitmining using two overclocked Sapphire TOXIC R9 280X 3GB GDDR5 cards the Seasonic X-850 (SS-850KM3 Active PFC F3) is not considered to be sufficient.
Heed Sapphire's recommendation of at least 1000 Watts or greater. You should not be continuously drawing over 80% of the PSU's total capacity or you risk drastically shortening the life of the PSU or risk triggering its thermal protection circuit.
If the PSU is unable to supply sufficient power or if the PSU's thermal protection is triggered then the whole system will shut down.
CrossFire isn't being used. The GPUs are not rendering images.