Pc in on and off loop

Telmir · 17 Dec 2015 at 15:25

I recently upgraded my pc and it was working fine, today I tried to add a USB 3 front panel which plugs in via sata power and then into the USB 3 header on my motherboard. But now the pc won't start, it gets into a loop of turning on and off, the power button won't even stop it unless I hold it then the led next to the bios battery flashes. It turns on for less than a second then off for about 2 or 3. Does anyone have any ideas?

I don't have my tools atm so can't take it apart but I've tried both with and without the now component and I get the same thing.

Components:
I7 4790k
Msi gaming 5 motherboard
Evga 750w power supply
Msi 980ti gold edition

Telmir · 17 Dec 2015 at 19:18

Yeah I only have one USB 3 header in the mobo and even when the now component is disconnected I still have the same problem but I may have knocked something so I'll try every plug and I'll always try resetting the bios too. If that doesn't work then I'll try my old psu so if that's the fault.

Telmir · 17 Dec 2015 at 19:39

Armadillo said:
Mine done that when the 12V for cpu wasn't in properly at both ends (fully modular supply).

Mines a fully modular psu too, what did you have to do to sort it? Also it was working fine until I tried to add that new part.

Telmir · 17 Dec 2015 at 20:10

Armadillo said:
Yep, just pushed it in properly after noticing it was not.

Maybe you knocked it/tugged it loose when installing the part. Might not be that at all for you. But it did cause my board to do the same as yours.

I'll have a look when I get in then cos the psu cables did get a bit of a tug. Thanks all I'll keep you all posted.

Telmir · 17 Dec 2015 at 22:30

OK so I tried the psu in a different pc and it works plus I've taken the gpu out and that does nothing so it looks like there is a problem with the mobo or something is shorting somewhere

Telmir · 17 Dec 2015 at 23:47

teenwolf said:
that behaviour is usually a short or the motherboard.

I'm thinking the same but I can't see anywhere that it is shorting , I have unplugged everything except case plugs and the CPU so it looks like it might be a replacement mobo :mad:

Telmir · 18 Dec 2015 at 00:28

ATIorNvidia said:
tried booting it with the motherboard outside of the case?

I'll try that tomorrow I haven't had enough time to do that.

And unfortunately my system bearly turns on for 1 second, the fans struggle to even get moving before it turns off again.

Telmir · 18 Dec 2015 at 11:19

So... I think I've found the problem, I've taken the mobo completely out and it looks like one of the pins in the USB 3 header had bent and is touching another pin.

Telmir · 18 Dec 2015 at 15:29

EVGAdominik said:
Did you try to bent it back and see if the board works again?

Its bent flat and I can't get hold of it at all.