R9 295X2 is my PSU powerful enough

Solution
Yes it can run your specs with that card.

A Radeon R9-295X2 needs 52 amps on the 12v + rail and a 800 power supply with 2 - 6+2 pin PCIE power connections.

Your Antec EXCEEDS the requirements.

OK so I managed to get my system back and running after the fiasco that is AMD Crimson drivers. I can run a few 3d marks then the computer will power off suddenly and reboot. I have had this before with my single R9 290 when play battlefront in 5760x1080 quite often but not so much at 1080p all with with the same setup and PSU. I don't think it is heat related as real temps shows everything within limits.