Bad Motherboard?

einzee · 31 Dec 2014

My brother's computer is identical to mine with the processor being the only exception. His is a quad core, mine is a six core. The compters were purchased together at the same time. Please refer to my specs if needed.

Here is my brother's situation:
When the power switch is pressed, the case and cpu fans come on at full speed. The video card fan also comes on along with the "HP" case light. Nothing else happens. Monitor only wakes up when unplugging it or plugging it in. There is also a tiny led light on the mobo that lights up.

The first time I looked at his computer I started the usual process of elimination. First, I tried resetting the BIOS by removing the battery and pressing the power switch. I then started unplugging any unnecessary components one by one until everything was unplugged. Each time I unplugged something I would try to start the computer. I ultimately ended up unplugging all connectors from the board. I then used a DVM to test the PSU and all appeared good with that. I plugged everything back in and still nothing. Just for the heck of it, I decided to pull the video card for a visual inspection and put it back in. After that, the computer started. So I figured that maybe someway, somehow there was a bad connection involving the card.

I get a call two days later.... same thing, nothing. So, this time I did the same as above except in the reverse order because the last thing I did before, worked. This time nothing worked and all of the original symptoms were still present. So my brother purchases a new video card and still, nothing. This time I go a little deeper and decide to pull the processor for a visual inspection. I put it back together and the computer starts up.

I'm starting to think that it may be a cold solder joint or something intermittently going bad. I also believe that, because whenever I was successful in the past, it involved actions by me that would have "flexed" the board slightly. And finally, the actions I performed to get the computer to start were at different locations on the board (video card/cpu) I've read that there is no real way to test and be absolutely 100% sure if a mobo is bad. I guess what I am looking for in here is some confirmation of my approach to and diagnosis of a bad mobo. Any feedback and/or suggestions will be greatly appreciated.

Thank you in advance.

Mellon Head · 31 Dec 2014

Your troubleshooting methods are sound. It does sound like doing anything that flexes the board seems to make it work. An easy way to test that theory would be to press it lightly the next time it won't start up and see if it goes then.

Motherboards are multi-layered boards, and they have traces on all of the layers. The traces are connected to each other, through the layers, by things called vias. They are little holes in the board which have copper in them to connect to the other layers of the board. It's possible, due to problems in the manufacturing process, that the layers can separate, damaging the vias and their connections. Pressing in the right spot on the board may temporarily reconnect the vias and the board works until it separates again. In that case, there is no fixing the board. It can't be repaired and is junk.

I think you're on the right track, but try a push on the board test the next time it fails. If it then works, for sure you need a new MB.

einzee · 10 Jan 2015

Update! I tried the poking and flexing suggestion above and just could not get the computer to start up. I did end up purchasing an exact replacement motherboard in hopes of not having to re-do all of the software and keep the cost of this repair down to a minimum. It worked! Windows Activation did show up and I was able to use my smartphone to input the long set of numbers and get the new activation code. There is also another issue that I will discuss in a new thread.

This one is solved and I thank everyone for their help.