PSU Fried?

[Drafter]

Very weird issue has occurred, never before has this happened to me.

I was down stairs cooking, PC was on and working, I come up stairs and it’s off. I try powering it on and it instantly turns off. We are talking like half a second and it’s off. So I assumed it was a PSU issue. I unplug the 6 pin out of my GPU (I have a 6 and an 8 pin) and it booted up. Nothing came on my screen, but it booted up. Does this mean my PSU is not giving enough power? When I plug the 6 pin back into the PC while it’s on, it instantly shuts down

PC specs
i9 9900k 8 cores 16 threads
GTX 2060
16gb DDR4 ram
1 TB HDD x2
250gb SSD
750W Power supply

PSU’s are much cheaper than a GPU. So if anyone who’s been doing PC’s for a long time knows, please let me know! Also, the power supply is pretty old. It was around 160 when I got it 5 years ago. (Might be older)

 

GPU not plugged in, PC boots up no display. 

[Drafter]

17 minutes ago, wONKEyeYEs said:

Maybe GPU?
Try removing GPU and running off onboard.

Yes, now it boots. So it’s the GPU? How can it be? Wouldn’t it just mean the PSU can’t power the GPU along with the motherboard? I’m able to get into the bios now, but I still don’t see how it’s a GPU problem. 

[Drafter]

25 minutes ago, wONKEyeYEs said:

To find that out you would try the GPU in another PC.

I did that, smoke started coming out...

[BlackManINC]

Yeah...what he said ...If the computer kept shutting down due the GPU bugging out, yet it works fine without it, then that means the power supply was doing its job, to stop the rest of your PC from getting deep fried extra crispy.