[SOLVED] ASUS P8Z77-V vga_led won't post 75% of the time

[MoriDuin]

My missus has a decent desktop built out of old parts from friends etc that she has been using for many years. Recently it has started failing to post (no output through HDMI) when booting but about 75% of the time it will boot up and work just fine. It gets stuck on the VGA_LED light on the motherboard when it does fail. This one has really flummoxed me as I cannot understand why it works some of the time and not always?

I have tried the following:

• Removing the GPU and trying onboard graphics
• Trying a different GPU
• Switching the RAM to single stick and in different slots
• CMOS reset the mobo
• Reset Mobo settings (think it was OC'ed previously)

Not sure what to do next other than buy a new 1155 motherboard, which I would like to avoid, the one she has is still an excellent board when we can get it working.

Specs are:
Asus P8Z77-V
i7 3770k
2 x 8gb DDR3
GTX 1050ti

Many thanks for any replies

 

[rgd1101]

and the make and model of the psu?

 

[MoriDuin]

Corsair VS550

Probably the newest part of the build, only about 2/3 years old

 

[MoriDuin]

I have today installed a mobo speaker from a different pc, it reads off one quick beep which according to the manual indicates :
VGA detected
Quick Boot set to disabled
No keyboard detected

I have also re-seated the CPU,
unplugged and plugged everything back into the motherboard,
Tried different PCI slots for the graphics card
On the occasion I could get it to post, I changed the priority graphics to go through PCI

Surely it must be either the motherboard or power that is failing/failed?

 

[rgd1101]

test with a different psu

 

[MoriDuin]

I have borrowed a 2nd PSU, still has the same problem

 

[rickypicky5]

No keyboard detected? If it's a USB keyboard, try a different USB slot.

I had the same motherboard and it died last year. Before it died, my USB devices would randomly disconnect and then connect. Ended up getting a new motherboard.

 

[MoriDuin]

Keyboard worked fine? An odd one, as an aside and closure to this thread Ive just decided to buy a Ryzen 5 and budget motherboard to replace it all, Ive spent a week trying to fix this so its not worth my time anymore