Question my pc doesn't turn on and there is a white light blinking on my graphic card

[Krrar]

Hello, I was using my pc then when I finished I turned it off. after two hours I needed it so when I tried to start the pc it did not turn on but there was a blinking white light on my GPU near the PCIe cable nothing else. the only thing that I did between these two hours was clicking the power supply switch and put it on (O) but when I tried to start it I put it back to (I)(I don't know if that effect something but that was the only unusual thing I did as I don't touch that switch) I spent two days trying to fix my pc but nothing changed I tried to took out the graphic card and the ram then put them all again, unplugged every cable on the motherboard and plugged it again, took out the CMOS for like five minute and put it back and even tried to touch the power switch pins on the motherboard with a screwdriver (though my pc start immediately after I plug it to the socket wall ) but nothing changed. I checked if the power supply was working by putting a paper clip between tow pins in the power supply 12 pin cable then turned it on and IT WORKED the case's RGB and fans worked as well as the power supply fan but when I plug the 12 pin back to the mother board nothing works but the blinking light on the GPU. I hope someone could help me or give me a advice its been two days and nothing worked if you had the same problem pleas tell me how you solved it.
my specs:
GTX 1660 asus tuff gaming
i3 10100f
asus prime h510m-k
16gb ram 1x16 corsair rgb pro
128 gb ssd
500 gb hdd
550 watt fantech shadow power supply

 

[Lutfij]

Welcome to the forums, newcomer!

I checked if the power supply was working by putting a paper clip between tow pins in the power supply 12 pin cable then turned it on then IT WORKED.
The paperclip test is flawed, it doesn't tell you how much power the PSU can effectively output to the entire system.

550 watt fantech shadow power supply
How old is the PSU in your build? Source(borrow, not buy)a reliably built 650W unit and see if the issue persists.

 

[Krrar]

Welcome to the forums, newcomer!

I checked if the power supply was working by putting a paper clip between tow pins in the power supply 12 pin cable then turned it on then IT WORKED.
The paperclip test is flawed, it doesn't tell you how much power the PSU can effectively output to the entire system.

550 watt fantech shadow power supply
How old is the PSU in your build? Source(borrow, not buy)a reliably built 650W unit and see if the issue persists.

I dont know how old is the PSU as that pc is used I bought it six days ago and its my first pc. it worked perfectly for the first four days though.
so does that mean that the issue is from the PSU? I thought fantech is a good brand.
I tried to unplug everything from the motherboard except the cpu and the cpu cooler and plugged the 12 pin and the cpu 8 pin then touched the power switch pins and nothing happened though the motherboard and the cpu doesn't take a lot of power