r9 270 with 460w psu

Maybe, but it will be close if it can.

Your PSU would need an available 6-pin PCIe connector for that card, and maximum combined +12 Volt continuous current rating of 28 Amps or greater.

You'll need to open up your PC and look at the volatge specifications on the PSU, as well as check to see if it has the correct 6-pin PCI Express supplementary power connector.
 


i have already looked inside my pc i have 2 pci 6 pins and my psu have 32amps on 12+