Yes you do , your are lacking the power and the amps.
A Radeon R9-280X needs 30 amps on the 12v rail and a 550 watt power supply with the proper PCIE power connections.PCPartPicker part list
/ Price breakdown by merchantPower Supply: XFX TS 550W 80+ Bronze Certified ATX Power Supply
($25.99 @ Newegg) Total:
$25.99Prices include shipping, taxes, and discounts when available