System shutdown under GPU load

[froots101]

Processor: AMD FX-6300 3.50Ghz (not overclocked) with Cooler Master Hyper 212 EVO heat sink and fan
Motherboard: Gigabyte GA-970A-DS3P AMD 970ATX
GPU: Sapphire Dual-X Radeon R9 270X 2GB
PSU: Corsair Builder Series CXM 600W Modular 80 Plus Bronze
RAM: Crucial Ballistix Sport XT 8GB (2 x 4GB) DDR3
Case: BitFenix Neos ATX Tower
OS: Windows 8.1 64Bit

I recently completed my first home build in a number of years, and the system has been running smoothly for a few weeks until about a week ago when it started to shut down without warning while gaming. Sometimes a game will play happily for a few minutes, and sometimes it happens almost as soon as any intensive GPU work is required. I had previously been playing the same games for hours without problem.

All drivers and OS updates are up to date. All fans are running and all connections are solid. There is little to no dust in the case because of the age of the machine.

So far I have:

Run OCCT CPU tests with no problem, with max CPU temperatures of 45 celsius throughout. Voltage rails from the PSU are at about 4.8-5V for the 5V rail and 12.1V consistently for the 12V rail.

Run OCCT GPU tests using DirectX11 at 1920x1080, fullscreen and with 4 shaders. This runs for about 30 seconds to a minute with voltages of 4.65V - 4.85V for the 5V rail and 12.1V consistently again for the 12V rail. It triggers the shutdown without fail every time. On one test run it triggered the shutdown before the full test screen even appeared.

Any suggestions? Is this just a faulty PSU or could it be something else?

 

[maestro0428]

Im guessing yeah, the psu doesn't have enough amperage or its faulty.