The Cooler Master 500 doesn't come with a PSU so it must have some other origin (some combo from newegg, amazon, etc.) I will assume it's the basic Cooler Master B500 http://www.coolermaster.com/powersupply/b-series/b500/
It supplies 24A on the +12V1 rail. The 270X peaks around 120-150W which is 10-13A so the power supply should handle it easily.