Lockup from Static Shock

[metafun]

I recently did a case swap and now my system will lockup if a static shock passes down a usb cable (ie plugging in my phone) or if one happens when I plug in headphones (to the headphone jack on my speakers).

When the system locks up, the GPU stops outputting to the monitor and the cpu fan briefly (the only fan connected directly to the motherboard) spins up. Using the restart button on the case I can boot the system back up and Windows complains about an unexpected shutdown.

Is the system not grounded properly? Is it related to the case swap?

The system is not overclocked and contains the following
i5-650
Asus P7P55D-E Pro
2x4GB GSkill DDR3 1333
Sapphire HD5770
2x 1TB Seagate HDD (Raid 1)
Corsair CX500M
Fractal Design R4 (swapped from a Antec 900)
Windows 7 Pro

 

[Ketchup]

Make sure all the motherboard screws are secure.

Can you be more specific about the USB connection? Is this the one on the back of the board, or is this one that connects to the front panel of the case?

 

[denis280]

Can you be more specific about the USB connection? Is this the one on the back of the board, or is this one that connects to the front panel of the case?

+1

 

[Tsavo]

It's not grounded properly somewhere down the line.

I had to completely disassemble a new build because even the slightest shock would cause it to crash. I found a mainboard standoff that was just a little taller than the rest and cause a very slight misalignment of the backplate. Fixed that, and the PC can take one hell of a static whallop without even blinking.

I've got another PC with a USB port on the front that will cause a shutdown is shocked. Since the only option is to replace the entire front USB board, I put black tape over it. The other ports on the front work fine and aren't bothered by static.

 

[Harvey]

That definitely sounds like a grounding problem.

1. Is your your wall socket properly grounded? That is, is the ground pin connected in the wall socket all the way back to the power mains?

In some older buildings, two conductor AC sockets have been replaced with three conductor sockets to accomodate current AC powered products, but the ground wire is not connected. If you have two conductor sockets, and you used a three to two wire adapter cheater cord, this could cause your problem.

2. Your AC cable may have a defective ground lead. Have you tried another AC cable?

3. With the machine unplugged, use an ohm meter to check for conductivity between the case and the AC ground contact. Do the same for black ground wires from the PSU to any of the various Molex power plugs.

4. Since this happens when you plug in a USB device, also check for conductivity between the metal outer shell of the USB socket and chassis ground.

5. Did you use the back shield plate that goes over the various rear panel connectors. If so, are any of them bent so they don't make contact with those sockets. The springy tabs on that shield plate are how they make ground contact with those connectors.

6. Did you use all of the mounting holes to mount your motherboard, and did you use metal standoffs (or at least, as many as possible)? On the bottom of your motherboard, you'll see that some screw holes are surrounded by bare, solder coated metal rings. These may intended to make contact with the chassis through metal standoffs. As Tsavo suggests, you may be able to fix this by simply unmounting and re-mounting the motherboard to the chassis.

7. Does the problem happen on all of your USB sockets, or just one or two? If you have several USB sockets, they are typically stacked two or three high in a single multi-socket assembly. Other USB sockets next to those may be part of another assembly. It's possible that a solder connection between a ground contact of one USB socket or assembly and the motherboard has cracked or weakened. This would affect all USB sockets in that connector assembly but probably not other USB connectors.

Hope that helps.

 

[metafun]

Make sure all the motherboard screws are secure.

Can you be more specific about the USB connection? Is this the one on the back of the board, or is this one that connects to the front panel of the case?

It is both of the USB 2 ports on the front panel.

That definitely sounds like a grounding problem.
.....
Hope that helps.

1) The wall socket is a 3 pin, as far as I know it is a proper grounded outlet. (The surge protector I'm using has a ground light and it is lit).

2) I don't have another AC cable.

3, 4) I'll have to get back to you guys on these.

5) I've used the back plate, and it looks ok.

6) I used all of the metal standoffs (which came with the case - 9 of them) that I have holes for on the motherboard. I'll double check the alignment.

7) I've not tried using the rear USB ports. I'll use those for a bit and see what happens.

Hopefully one of these will solve the issue.

 

[Ketchup]

Then yeah, there is either a short in one of the cables that runs from the motherboard to those front sockets, or the little board that connects the socket to the cable.

 

[metafun]

I did the conductivity tests on the case and the front panel usb ports and it looks fine.

I'll use the rear usb ports for a bit and see if that results in any shocks/lockups. Then I'll move on to re-mounting the motherboard.

Then yeah, there is either a short in one of the cables that runs from the motherboard to those front sockets, or the little board that connects the socket to the cable.

A short in those cables or the front-panel board makes sense for the USB issue, but not when I plug the headphones into my speakers (since the speakers go to the green-jack on the back panel).