[SOLVED] PC won't boot up with case, works without the case.

[TitaniumHawk]

My PC won't boot up when everything is assembled, the error it shows is 'usb device over current status detected' and shuts down after 15 seconds.
There is mild shock when I touch the PSU, the motherboard and the thumbscrews on my PC.
I decided to disassemble my PC and try to boot it. I removed everything, and kept my PSU, motherboard and my hard disk with windows on it on my table connected, and it worked properly, no problems at all, could even play games with normal FPS.
So I assembled it again, and it showed that error again with the mood shocks. I tried a few things to find out the problem or know if and where a short is.
It happened out of nowhere, I've used this PC for 4 years.

1. Removed all the screws on the motherboard that attach it to the case.
2. Removed various equipments one by one, all the fans, the DVD Drive, hard disks.
3. Unscrewed the PSU from the case
4. Removed the GPU.

I can't find what the problem is here.
My specs are
Asus H97 Pro Gamer Motherboard
Cooler Master B600 600W PSU
Intel i7 4790K
Sapphire AMD Radeon Dual-X OC Edition R9 270X 4GB GPU
G.Skill DDR3 2x4 8GB RAM

 

[jay32267]

What if you disconnect all the USB ports at the MB?

"There is mild shock when I touch the PSU, "
I would check that the case is grounded.
If it is....and you are still getting a shock....then it's you that is charged up and it won't hurt anything.

 

[TitaniumHawk]

What if you disconnect all the USB ports at the MB?

"There is mild shock when I touch the PSU, "
I would check that the case is grounded.
If it is....and you are still getting a shock....then it's you that is charged up and it won't hurt anything.

Yeah I tried with just power cord and hdmi cord, still did not boot. And yes the PSU is grounded

 

[Paperdoc]

My suspicion is you forgot the stand-offs. Every case comes with stand-offs used to establish clearance between the case's mounting plate and the back of the mobo. They usually look like round brass pieces about ¼" long with a threaded hole in one end, and a threaded shaft out the other end. There are several common styles of mobos, and the all have some pattern of mounting holes in them, but they can be different. The case mounting plate comes with many holes pre-drilled and threaded for mounting. Some come with the stand-offs separate in a bag and they need to be installed. Others come with the stand-offs already installed in a common layout suited to many but NOT all boards. What is essential is that you make sure that the stand-offs all are placed in case holes so that they match exactly where the MOBO mounting holes are. Ideally there should be a stand-off under every mobo mounting hole, But MORE IMPORTANTLY, there must NEVER be a stand-off under the mobo where there is NO matching mounting hole. And yes, you MUST use the stand-offs. Do NOT fasten the mobo directly to the case mounting plate.

Look carefully at the mobo mounting holes - often three rows of three each. You will see around each one little metal fingers like a flower. The intent is that the screw through this hole into the stand-off will be a Ground point for the mobo. But there should never be a Ground connection anywhere else (except via the power cables). So the stand-offs need to be placed in the case mounting plates' pre-drilled holes just right. Position them as you think they should be to match the mounting hole layout of the mobo. Then temporarily position the mobo in place and check very carefully that they all match exactly, and there is NO stand-off under the mobo where there is no matching hole. When you're sure they are all correct, install the mounting screws.

I once had an odd related incident. I had removed the mobo from the case for something else and re-installed it. Before going further I inspected and found a weird thing. Looking at all the mobo ports that peek through the metal panel on the back of the case, I found one where the springy metal finger of the panel's opening had slipped INSIDE the connector shell instead of contacting the outside. This touched a socket contact creating a short circuit to Ground. I had to remove and re-install the mobo again to get it right.

 

[Deleted member 14196]

yeah, case is shorting with the motherboard for sure somewhere.

 

[TitaniumHawk]

My suspicion is you forgot the stand-offs. Every case comes with stand-offs used to establish clearance between the case's mounting plate and the back of the mobo. They usually look like round brass pieces about ¼" long with a threaded hole in one end, and a threaded shaft out the other end. There are several common styles of mobos, and the all have some pattern of mounting holes in them, but they can be different. The case mounting plate comes with many holes pre-drilled and threaded for mounting. Some come with the stand-offs separate in a bag and they need to be installed. Others come with the stand-offs already installed in a common layout suited to many but NOT all boards. What is essential is that you make sure that the stand-offs all are placed in case holes so that they match exactly where the MOBO mounting holes are. Ideally there should be a stand-off under every mobo mounting hole, But MORE IMPORTANTLY, there must NEVER be a stand-off under the mobo where there is NO matching mounting hole. And yes, you MUST use the stand-offs. Do NOT fasten the mobo directly to the case mounting plate.

Look carefully at the mobo mounting holes - often three rows of three each. You will see around each one little metal fingers like a flower. The intent is that the screw through this hole into the stand-off will be a Ground point for the mobo. But there should never be a Ground connection anywhere else (except via the power cables). So the stand-offs need to be placed in the case mounting plates' pre-drilled holes just right. Position them as you think they should be to match the mounting hole layout of the mobo. Then temporarily position the mobo in place and check very carefully that they all match exactly, and there is NO stand-off under the mobo where there is no matching hole. When you're sure they are all correct, install the mounting screws.

I once had an odd related incident. I had removed the mobo from the case for something else and re-installed it. Before going further I inspected and found a weird thing. Looking at all the mobo ports that peek through the metal panel on the back of the case, I found one where the springy metal finger of the panel's opening had slipped INSIDE the connector shell instead of contacting the outside. This touched a socket contact creating a short circuit to Ground. I had to remove and re-install the mobo again to get it right.

Thank you for replying, I shall try this now

 

[TitaniumHawk]

I found the problem and it was the front panel's usb 2.0 that was causing the short, I removed the motherboard's connector to it and everything started working properly.
But I still am getting a mild shock when I touch the thumbscrews. And when I plugged in my phone into the front panel's usb 3.0, i got a shock from my phone. Any suggestions?

 

[Paperdoc]

If you are getting a mild shock from the case of your computer, some item somewhere is plugged into an electrical socket wrong. In modern electrical systems the outlets all have three holes - two vertical slots, and a third round hole. The round one is the Ground connection and there is only one way to plug a 3-prong plug into that outlet. But there's a further detail. Look closely at the two vertical slots and you'll see they are a different height. If the outlet is mounted so the round Ground hole is at the bottom of the triangular arrangement, the vertical slot on the LEFT if higher (wider) than the one on the right. The WIDER slot (left) is the Neutral one, and the narrower one is the Hot line. This is important if you are plugging in a cord with a TWO-prong plug. That plug also should have one prong wider than the other so you can only plug it in one way. These design features ensure that all devices are connected properly to the power source.

If you have older electrical sockets they may not have these features. Also, of you have some 2-prong plugs, they may not have different sizes of the two prongs. In either of these cases it is possible to connect a device the "wrong way". In SOME device designs the Neutral line is connected to the device chassis as if Neutral and Ground are the same thing. (It should not be done this way, but some are.) In those cases connecting that device's cord the "wrong way" can cause the problem you experience. Moreover, in a computer system there often are several devices all plugged in individually but interconnected by signal cables that all treat their chassis as "Ground" and use them to connect to the shields of each signal cable. Thus the chassis of all units tend to be connected together, so if even ONE of them is "wrong", the entire system can be electrically "live".

To sort this out, follow this sequence.

1. Check your system with no changes, and verify you DO get a mild shock off the case to start.
2. DIS connect all the interconnected device signal cables so that none of the peripherals is connected to your computer. Now check again whether you are getting a mild shock. If you are then the power cable to your computer is the first suspect. If it has a 2-prong plug on its power cord, try unplugging it and turning the plug over, then plug back in. This assumes you have it plugged into a wall outlet. IF you have an extension cord or multi-outlet power bar involved, ensure it also is checked for "wrong-way" connections. Once you eliminate the small shock symptom at the computer, proceed with the rest.
3. Now, ONE at a time, re-connect the various peripheral device signal cables to your computer. For each, check whether the shock symptom has re-appeared. If it has, then go to the power cord for that added device and try turning its power plug over and re-connecting to eliminate the shock.

4, When you have all your peripherals re-connected and you still get NO small shock, you have solved your problem.