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A few weeks ago, I moved my main computer into a different room, and hooked it up with long (10m) HDMI and USB cables so I could compute in peace.
Since then, I've also been getting the occasional BSoD, mainly when rendering 3D accelerated stuff. Temperatures look fine, so I was wondering: hypothetically, could a weak HDMI signal cause system errors? What about USB?

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up vote 2 down vote accepted

Weak HDMI or USB system should not cause BSODs. However, there are additional issues you have to consider:

  1. There might be bugs in video card or USB drivers that don't handle well the problems that long cables introduce: more noise, possible disconnects due to a weak signal, etc.

  2. Longer cables also mean more EMI, unfortunately. If your cables' shielding is unsatisfactory, electromagnetic noise picked up by these cables might cause hardware faults. Both temporary and permanent (less likely).

    You should check how you routed these cables. Don't put power and data cables together, don't route behind your microwave, etc.

  3. All circuits in your house should have the same "earth". If this is not so, and you connect two devices connected to two receptacles with a potential between their earth levels, you'll get issues.

How to troubleshoot

I suggest you put all your devices in one room, as close as possible, temporarily, but connect them using your long cables. See if you're still getting these problems. If yes, switch to short cables and see if they are gone. This way you can figure out if your cables are to blame or your problem is somewhere else.

If you have EMI issues, sometimes putting clip-on ferrite beads on your data cables, on both ends, close to the connectors, helps.

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Your third point is a good one. Will see if I can do anything to improve the earth situation. Thanks. – oKtosiTe Dec 14 '11 at 21:24
@oKtosiTe: This is a rare problem, more common in older houses with lots of renovation. But if you do have it, better get help of a qualified electrician, this is a serious issue. – haimg Dec 14 '11 at 22:07

It's possible. If the app is expecting a device to be somewhere and the signal drops, a poorly written driver could be incapable of handling that gently, and you'd get a BSOD.

I'd update all the system drivers first off.

If the issue persists, the true test would be to reconnect to the computer using the shorter cables and see if the issue goes away.

Using higher quality cables may also help prevent the issues as they may be able to carry the signals further without interference.

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I figured I should probably troubleshoot with short cables, but with the location of the box, and its portability, it's going to be a bit of a PITA... ;-) – oKtosiTe Dec 14 '11 at 21:21

In theory... yes... but highly unlikely. Video cards (and all electronics) that meet FCC requirements are supposedly designed to handle any reasonable amount interference gracefully. What kind of HDMI cable are you working with? Is this a Category 2 cable? Category 1 cables are cheaper and may not work properly at longer lengths + high resolution. It's more likely that either A) the longer-length of cable is forcing some component on your video card to work harder and it is not behaving properly.... or B) you might have a cold-solder joint someplace that formed by knocking your PC around during the move.

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Are you only using USB cables with no hubs or repeaters in between? If so, the 10 m USB cables are probably violating the USB specification and that could lead to problems with USB devices. If the device on the other end is sensitive to voltage, it could be turning on and off at unpredictable intervals or its microcontroller may suffer memory corruption.

USB repeaters may also cause considerable problems if the device has poorly written drivers and isn't expecting to negotiate lower link speed.

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