PC Restarts R9 280X Toxic

[Del09]

My PC restarts without any warning or BSOD since installing the graphic card. Weird thing is that it happens at the same scene of some game/application. 3DMark Fire Strike for example, the restart happens every time the fiery monster drag its sword on the floor but if I underclock my GPU clock, the time before my PC will restart will increase. The lower i change the clock rate of my GPU clock, the longer my PC will run. If i run 3DMark Fire Strike with the same frequency the second time, PC will restart on the same scene. I don't think it an overheating issue because I enable logging with GPU-Z while running 3DMark Fire Strike and the last recorded temp is around 70-80 degree celsius. Can't really remember. I also ran furmark, temp has gone over 80 something and no restart and artifacts. I think it is the PSU because the GPU requires 750W. I have 600W and it's not really an expensive one. It also happens with BF4. Other benchmarking tools works well like Unigine Heaven 4.0 and Valley 1.0. No Artifacts/Freeze what so ever before restart. Considered installing latest driver and the latest driver available on the sapphire website where you can download drivers. Also updated the BIOS of my MoBo. I also tried reformating, switching to Win8.1. I really hope it's not the graphic card. It was expensive; for me atleast. sorry about my english. Another thing, I'm from a tropical country if its relevant. ambient temp goes over 30 at day.
Here's my PC specs:
Intel i5 2400 3.1Ghz
4GB RAM
Asus P8H61-M LE
Sapphire R9 280X Toxic
PSU: FSP600-80GHN - FSP Groups Inc.

 

[Kekoh]

Yeah, that definitely sounds like a PSU issue. It's probably trying to draw too much power at the specific scene and the PSU just can't supply it.

It says it has quad 12V rails, which is not what you want for a gaming rig. The 12V rails probably do not have sufficient amperage. You want a PSU with a single 12V rail that has high amperage.

 

[Del09]

OK. I'll try to buy a new PSU. Will update when i get one. Thanks.

 

[T-Bag]

Yeah. It sounds like a PSU issue. And a small thing to keep in your mind. When you're building a "Gaming Rig", get a quality PSU from a good brand like Sea Sonic. Sea Sonic S12II 620 watt is a good one.

 

[Kekoh]

Corsair, XFX, Antec are also good PSU's.

HardOCP is a good website to check for PSU reviews. They do an excellent job fully testing them.