[SOLVED] PC shuts off unexpectedly


Jun 17, 2016
Here is my Build:
Processor: AMD Ryzen 7 3800X (NEW)
Motherboard: B450-A PRO (NEW)
Graphics Card: nVidia GTX 1060 6 GB (1 Year old)
RAM: G.SKILL Aegis 16GB (2 x 8GB) 288-Pin DDR4 SDRAM DDR4 3000 (PC4 24000) Desktop Memory Model F4-3000C16D-16GISB (NEW)

Power Supply: CORSAIR TXM Series, TX750M, 750 Watt, 80+ Gold Certified, Semi Modular Power Supply (1 year old)
Cooler: Ryzen Stock Cooler (Wraith Prism) (NEW)
Hard Drive: ST3320620AS
SSD: PNY CS1311 240 GB

Here is my problem, my computer shuts itself off. I thought it shut itself off because of a loose cable, but I unplugged and replugged all of the cables inside and it still has this issue.
I ruled out thermal issues through looking at the temperatures and the fan is still spinning consistently.
Whenever I plug a USB cable into the back and put some kind of pressure on the back plate of the motherboard on the case, it shuts itself down. But it recently just shut off without any sort of shaking or changes to the USB ports in the back.

What would you guys think this problem is and how do you recommend I fix it?