PC Won't Post, Don't Know Why

[Sir Topham Hatt]

Short version:

 

PC won't post. Changed motherboard, worked. Then reset PC and now doesn't work.

 

 

Longer version:

 

I was upgrading my ati graphics card driver when the installer seemed to crash.

I quit out of it and when clicking on START, nothing happened but the screen flickered a few times and made the "you've unplugged something sound".

Restarted the PC.

When it came back on, Windows had corrupted somewhere and it went to recovery. Couldn't reset locally so had to use another PC to make a Windows Tool. So shut down while I did that.

Came back and the PC wouldn't even post.

Tried a few different things, re-seating the graphics card, ram, both were fine. Tried plugging an HDMI cable direct to the motherboard, no display. What's strange is the power button no longer turned the PC off if I held it. I noticed the graphics card fans were no longer spinning, which made me think there was a power issue.

 

Used a multimeter to test the motherboard outputs of the power supply and everything seemed okay there. To be fair, I didn't test the power cables going to the graphics card.

 

So bought an identical motherboard and fitted it.

Booted but no display using motherboard HDMI.

 

Fitted the graphics card and what do you know, it posted!

Went through the Windows recovery and thought I'd use the Recovery tool on the stick I'd made. Then decided that perhaps a local install would be better - it gave me the option to shut down, so I did.

 

Restarted the PC and we're back to no display again.

 

I really don't understand it.

 

I tried pulling the power cable out and the CMOS battery and leaving it for 5+ minutes, but still the same.

Tried fitting a jumper to the CMOS clear thing and still no joy.

 

When I was able to post and see the Bios settings, I changed the time and turned off the motherboard LED that was it.

 

I wonder if the motherboard isn't sending a signal to the graphics card to start and thus it doesn't so no display.

 

Not sure why it doesn't display from the motherboard though?

 

Motherboard is a Gigabyte B450M DS3H. 

 

Any pointers would be great.

[Sir Topham Hatt]

Update:

 

Loosened the graphics card heat disappating unit (can't remember the name) and reseated the screws.

 

Left it for a few hours.

 

Then, plugged it back in on the off chance it may work. What do ya know, it's now working.

 

Windows is busy re-setting at the moment, which is fine - I have all afternoon. Although a little weary as it was at 39%, then jumped to 86% and was there for about 5 minutes.

 

Then the PC restarted. Now it's busy installing. Wish I'd have taken regular reports on what software I installed!

 

Not sure what was going on but I'm a little afraid it may do the same again, despite being fine for 2/3 years.

 

The only thing I changed back from the default setting on the motherboard was some sort of motherboard LED for "cool" looking cases. Mine is under the desk so couldn't care less.

 

Just a shame as I have to update the BIOS, which I remember was tricky last time, although with this new motherboard, I have a nice graphical BIOS - the one before was standard all text based so I guess I'd changed a setting somewhere.

 

Then again, maybe I shouldn't bother with updating it - works fine as it is.

[Sensi]

Do you have a spare PSU? If so, could be worth using it to see if you get the same no post issue. Good luck ✌️