ICH4 killed by RC filter on front-panel USB port?

[saltyf]

Installed my old AOpen i855GMEm-LFS into a brand new In-Win Mt. Jade case. It was a nice fit, and it actually worked fine for a few days. Until I shut down the system for the first time (as opposed to S3 Standby).

Next morning it refused to turn on. Looked like circuit protection was going off. Fans were spinning for 1/2 a second then stopped. I narrowed down the problem to the front-panel USB headers. With these unplugged the system booted just fine. Disconnected the USB cables at front-panel side and decided to test at with just USB cables plugged in - everything was fine. Connected the front panel again, pressed Power, the system turns on (hot start?). A second later I hear three quiet pops and feel a burning smell. Investigation showed I now have a small brown hole in my ICH4 chip. Motherboard is dead.

First thoughts - a short-circuit in the USB ports, although I never even touched them and everyone in the household swears the same. Upon testing the front panel pins with a multimeter I couldn't find anything wrong with them. Visual and olfactory inspection revealed nothing. The only weird thing I could find were the 100uF caps between the USB +5V and GND leads. Could these be the culprit?

Should I take this issue up to the computer case retailer/manufacturer? I guess it will be very hard to make either of them reimburse me for the damaged motherboard?

 

[saltyf]

More importantly, should I worry about putting a new moterboard into this case? I was planning to build a GA-MA78GM-S2H / 4450E based machine to replace my old one.

 

[Aluvus]

Decoupling capacitors between power and ground are perfectly normal, although being part of the case or its associated parts is a bit unusual. If one of those capacitors failed (look for bulging, oozing) bad things could happen.

Not sure how you decided on a USB issue, although that's possible. I would make sure you did not inadvertantly connect a Firewire header to a USB port on the case (or vice versa), as that can make very bad things happen.

 

[saltyf]

I know they are normal, it's just all the cables I've seen before were just wires leading to a connector with open leads. Which is also the main reason why bad things shouldn't happen (with some exceptions) when you plug a USB cable into the wrong header. That is, until you insert a USB device.

Anyway, no leaking caps, no obvious damage/defects anywhere, no shorts, and I'm sure I've inserted the headers right (color-coded, keyed connectors, double checked the pin-out, etc.), besides, the system worked fine the night before.

Still scratching my head.

 

[EliteRetard]

Originally posted by: saltyf
Installed my old AOpen i855GMEm-LFS into a brand new In-Win Mt. Jade case. It was a nice fit, and it actually worked fine for a few days. Until I shut down the system for the first time (as opposed to S3 Standby).

Next morning it refused to turn on. Looked like circuit protection was going off. Fans were spinning for 1/2 a second then stopped. I narrowed down the problem to the front-panel USB headers. With these unplugged the system booted just fine. Disconnected the USB cables at front-panel side and decided to test at with just USB cables plugged in - everything was fine. Connected the front panel again, pressed Power, the system turns on (hot start?). A second later I hear three quiet pops and feel a burning smell. Investigation showed I now have a small brown hole in my ICH4 chip. Motherboard is dead.

First thoughts - a short-circuit in the USB ports, although I never even touched them and everyone in the household swears the same. Upon testing the front panel pins with a multimeter I couldn't find anything wrong with them. Visual and olfactory inspection revealed nothing. The only weird thing I could find were the 100uF caps between the USB +5V and GND leads. Could these be the culprit?

Should I take this issue up to the computer case retailer/manufacturer? I guess it will be very hard to make either of them reimburse me for the damaged motherboard?

So you have my luck, and my avatar...coincidence? I think not! I can only offer you this advice: Do not touch anymore elctronic devices.

Trust me, I responded the same way and boy do I regret it. Im only alive so I can suffer more. Perhaps you can get a helper monkey to do things for you...as long as luck doesnt transfer (or worse, evil helper monkey)

 

[tcsenter]

This was an issue with ICH4 and early revisions of the ICH5. I seem to recall Intel adding some ECN blurb to the ICH4 or ICH5 datasheet or specification update. The following is an archive snapshot from a now-defunct FAQ on Gigabyte's website:

The ICH4/5 SouthBridge chipset on my Intel motherboard appears damaged or "burnt". How did this happen?

The GIGABYTE Global RMA Service Center has recently become aware of the randomly occurring risk to ICH4/5 SouthBridge chipsets on Intel® motherboards to become damaged or "burnt" when a USB device is connected. Please read the following paragraphs to learn more about this issue.

Why did this happen?

There are three likely causes:

• Accumulated static electricity from the human body may have been transmitted to the ICH4/5 SouthBridge chipset when connecting a USB device if it has not been "grounded".

• A connected USB device does not have any static electricity protection.

• Accumulated static electricity in a front-panel USB port that is not properly "grounded" with the PC casing.

Usage Tips

• Avoid touching the USB connector.

• Release static electricity within your USB device by touching the USB connector to any metal surface before plugging it into your computer.

• Use rear-panel USB ports on your PC whenever possible.

• Use a three-pronged electrical cord to connect a power supply to your PC.

• Use only approved or certified power supplies.

 

[saltyf]

To: tcsenter

Interesting info. I guess static electricity could have been the thing that killed it.

But this still doesn't explain why the system refused to turn on before that.

 

[tcsenter]

Right, because a damaging ESD event only makes things go 'pop', but won't have any other impact on function? OK!

 

[Modelworks]

This is really odd
There are supposed to be fuses between the USB connectors and the motherboard traces.
Sounds like Aopen did some cost cutting.

Was there anything on the bottom of the board that could have shorted ?