Question PC Wont Turn on, Only Power Led Turn on for a brief second

[ijoin]

Hi,

So I'm trying my parent's old pc
Yesterday it worked well and I can play around for 2 hours
Today when I want to turn it on again, nothing happened, the power LED indicator only turned on for like less than a second, only a blip

It is a Haswell CPU with Gigabyte board

I tried the PSU+RAM and it works well on other PC, but since I own no haswell system, I can't try the board and the cpu

Any idea why?

I already tried with other PSU, replug the CMOS battery and still, it only blink once everytime I turned it on


update --
disconnected the 4pin connector to the cpu, now the cpu fan turn and psu response but still, after 2 sec it turned off again and repeated for 2 times and then off at all

Whenever I plug in the 4pin connector to the cpu, the pc totally dies

 

[gutsygoat]

You could try resetting the bios, (turn the PSU off for 5mins, take the CMOS battery out (usually hidden under the graphics card) Then hold the power button for atleast 30 seconds. Once this is done, put the CMOS battery back in and wait out the rest of the 5min.

 

[ijoin]

You could try resetting the bios, (turn the PSU off for 5mins, take the CMOS battery out (usually hidden under the graphics card) Then hold the power button for atleast 30 seconds. Once this is done, put the CMOS battery back in and wait out the rest of the 5min.

already did it but nothing