GPU problem or Motherboard problem?

[How Do I Report]

GPU: EVGA GeForce GTX 760
CPU: Intel i5-4670K
RAM: 8 GB G.SKILL 240 pin DDR3 SDRAM
PSU: SeaSonic S12II 620w Bronze
Motherboard: GIGABYTE Z97X-UD3H

1 month ago, my GPU stopped outputting while it was in the first PCI-E slot. I moved it to the second and it has outputted to my monitor ever since.

However, 2 weeks ago I started noticing moments of choppiness in League of Legends. (Never happened previously.) I didn't think too much about it though, it was very minor. On monday I installed Overwatch, and it is incredibly choppy, even on minimum settings. I also tested Skyrim and it is unplayable. League has also been getting notably worse, even on minimum settings.

TLDR: 2 weeks ago games started getting slightly choppy and low frame rate. Fast forward to today, and games are almost unplayable. Should I replace my GPU? or is my Motherboard possibly malfunctioning?

 

[cin19]

Recommend to try use onboard intel iGPU to play the LOL first, and you will know the problem is from the gtx760 or something ( the MB) else at least, because you can run the LOL with that onboard iGPU.

If you can play the LOL with onboard iGPU, then try update the chipset driver first, get the driver from gigabyte or intel https://downloadcenter.intel.com/download/25094/Chipset-Intel-Chipset-Device-Software-for-Intel-NUC that you make sure the problem is not the software because the chipset driver comes with the pcie controller driver.

If after done the update and you still have problem with the gtx760, may 1) test the gpu in other pc, make sure it works fine or not. 2) we know the seasonic PSU is very good, but may still go into the BIOS to check the +3.3V, +5V, and +12V. Make sure it is fine. PSU Voltage Tolerances http://pcsupport.about.com/od/insidethepc/a/power-supply-voltage-tolerance.htm