Question Troubleshooting mystery - Two different comps will not start inside the case, but work fine outside the case.

[fenns_treasure]

I have a mystery. I have two computers that are both not starting in their case, but will start and run the OS when everything is set up outside the case (breadboard style). I am at loss for further troubleshooting. Here are the details.

Comp #1
Brand new build, mid tower size. Power supply cords proved to be short, so I took my PSU from my office and put it in this build. After it was all hooked up, it would not start, only the PSU fires up. I took everything out and set it up outside the case, and it works fine; I installed Win10 and everything. I put it back in the case, and it won’t start.

What I have tried:

• Reinstalled standoffs, checked board placement, took I/O board out of the back, removed GPU and used onboard graphics, removed any other peripherals, so all it has is the mobo cable, CPU cable, and heat sink fan and one stick of RAM. Still doesn’t work when installed in case.
• Unscrewed PSU so it was still not touching the case and without any screws in it, but still powering board. Comp still won’t start.

Again, everything works when outside the case.

Comp #2
This is a two year old rig, micro ATX, used daily. All I did was swap PSUs, so the cables would fit in each rig. After swapping PSUs, it would not work in the case, it won’t even start up the fans. I took it out and set it up breadboard style and it works fine. I tried the original PSU again, and it too works outside the case, but not inside. I then tried the new PSU in the new build again. I also tried all the steps of Comp #1, with the same results.


So, both comps will work outside the case, but not inside the case, with either PSU.

I know this is some kind of charge/short issue, but I don’t know what. If it was a residual charge in the PSU, it wouldn’t start outside the case either, at least I don’t think it would. I also have a new APC, and it is flashing a red light indicating a charge on my house wiring, but again, both builds will work outside the case but not inside the case, whether plugged into the APC or just the wall. Both comps are in separate rooms too. Also, I have three builds downstairs that are running fine, so even if there is some charge on my wiring, it’s not affecting them. Besides, how can it be a simple case short when it’s happening to two comps?

Any ideas? I am out of ideas on this one. I can post the details of each build, and I will if you want, but I am guessing it doesn’t matter what my parts are given my situation. Thanks for any help.

 

[CountMike]

I have a mystery. I have two computers that are both not starting in their case, but will start and run the OS when everything is set up outside the case (breadboard style). I am at loss for further troubleshooting. Here are the details.

Comp #1
Brand new build, mid tower size. Power supply cords proved to be short, so I took my PSU from my office and put it in this build. After it was all hooked up, it would not start, only the PSU fires up. I took everything out and set it up outside the case, and it works fine; I installed Win10 and everything. I put it back in the case, and it won’t start.

What I have tried:

• Reinstalled standoffs, checked board placement, took I/O board out of the back, removed GPU and used onboard graphics, removed any other peripherals, so all it has is the mobo cable, CPU cable, and heat sink fan and one stick of RAM. Still doesn’t work when installed in case.
• Unscrewed PSU so it was still not touching the case and without any screws in it, but still powering board. Comp still won’t start.

Again, everything works when outside the case.

Comp #2
This is a two year old rig, micro ATX, used daily. All I did was swap PSUs, so the cables would fit in each rig. After swapping PSUs, it would not work in the case, it won’t even start up the fans. I took it out and set it up breadboard style and it works fine. I tried the original PSU again, and it too works outside the case, but not inside. I then tried the new PSU in the new build again. I also tried all the steps of Comp #1, with the same results.


So, both comps will work outside the case, but not inside the case, with either PSU.

I know this is some kind of charge/short issue, but I don’t know what. If it was a residual charge in the PSU, it wouldn’t start outside the case either, at least I don’t think it would. I also have a new APC, and it is flashing a red light indicating a charge on my house wiring, but again, both builds will work outside the case but not inside the case, whether plugged into the APC or just the wall. Both comps are in separate rooms too. Also, I have three builds downstairs that are running fine, so even if there is some charge on my wiring, it’s not affecting them. Besides, how can it be a simple case short when it’s happening to two comps?

Any ideas? I am out of ideas on this one. I can post the details of each build, and I will if you want, but I am guessing it doesn’t matter what my parts are given my situation. Thanks for any help.

Looks to me like there's a short somewhere when you install it in the case. Most often that is caused by improper placing of MB standoffs.

 

[fenns_treasure]

Looks to me like there's a short somewhere when you install it in the case. Most often that is caused by improper placing of MB standoffs.

Thanks for the reply. I did remove and reinstall all the standoffs in both cases as part of my troubleshooting. It still didn't work. Are there any things you can buy that insulate the standoffs from the case, but still allow you to screw them in? I am not sure what else I can that would account for the case shorting the mobo.

Plus, this is happening on both computers.

 

[Mtop]

You can purchase plastic standoffs (may need hardware at both ends.
You can try a small plastic washer between standoff and MB (PIA)
I would install my standoffs on MB out of case and look close at each one to see if any are touching a trace or solder connection.
Also I had a board at one time that would short to the case at edge where all the connections are (usb, vga, sound) the board kinda just touched the case edge. (I insulated with a piece of plastic.)
A possible quick fix. spray some clear spray paint on back side and let dry.
(dont spray everything tho just the traces & dont let it drip thru holes)

 

[CountMike]

All modern MBs are made so they are grounded thru standoffs.