Consolemasterracelol :
I'm currently running 1x R9 270X with 500 W psu and I'm getting another 270X. Would 630W be enough or would I really need to get a 650W?
Power consumption AMD Radeon R9-270X
System in IDLE = 116W
System Wattage with GPU in FULL Stress = 283W
Difference (GPU load) = 167W
Add average IDLE wattage ~10W
AMD R9 270X - On your average system the card requires you to have a 500 Watt power supply unit.
AMD R9 270X Crossfire - On your average system the cards require you to have a 700 Watt power supply unit as minimum.
(Credits Guru3D.com)
To answer your question.
Yes you can but, get a very high quality PSU like the SeaSonic X Series PSUs
Minimum
SeaSonic X Series X650...