Will GTX 760 or R9 270x Work with CORSAIR GS600

Hi there
im planning to upgrade my GPU to GTX 760 or R9 270x but it will reach my limited budget if i get a new psu so im thinking of rescue my old GS600watt for GTX760 or R9 270x since it requires minimum 500watts? is enough power? what about water cooling?

my build :
AMD FX 8150 - CPU
BIOSTAR TA 990FXE - MOBO
CORSAIR VENGENCE 2 X 4 GB 1866MHz
CORSAIR H100I LIQUID COOLER
2 * 2 TB WD HDD
SAMSUNG EVO 128 GB SSD
CM STORM TROOPER

thanks in advance