I've got a few strange symptoms on a machine I built:
I think I've got a ground loop, maybe at my cable modem.
I found an article on solving ground loops, but I'd love to confirm that these symptoms are all related to that issue, and make sure I'm not dealing with multiple loops.
I've got an ohmmeter around somewhere, but not a lot of experience using it.
(I assume I should be stripping the machine down, disconnecting and unplugging it, and adding components one at a time to test...)
Any general advice on hunting down the issue(s)? Anything I should be paying special attention to? If it is only the cable modem, what's the best way to solve it -- an isolator?
If you already suspect the modem, I'd suggest that rather than stripping the machine down and adding one component at a time, it may be easier to first remove the modem and see if that fixes it.
No concrete suggestions on what to measure tho.
I had a computer a couple years ago which wouldn't reboot if a flash drive (or anything USB with storage) was plugged in. That part turned out to be a BIOS setting, it was trying all 'removable drives' before the hard drive, and the hard drive turned out to be the boot device of last resort after a 10-minute time out (it was a freaky BIOS, let me tell you).
The sound card issue could be grounding, but a simple check would be the volts (not ohms) between the bare metal of the case and a known ground, like an outlet ground pin if you know that's good or a water pipe. Then you could check voltage between your PC and the cable connector as well. Running your ethernet cable through a UPS 'filter' should match that ground to the PC's as well.
The audio connection part: Are you running Vista/Windows 7? Windows post-Vista contains 'protection' routines that disable your analog audio outs when 'protected' (hi-def) content is played with a media player. Only digital (in this case your digital out and an internal Aux) outputs are supported so that you can't redirect audio data to a tape recorder (the 'analog hole'). More here.
So, at least I've given you the possibility that all three of your issues are completely unrelated. I certainly can't prove that they aren't related, but these are just the first three things that popped into my head.
Something (a head) once fell onto my computer and hit a USB drive plugged into the front. Now, whenever something is plugged into that port, the computer restarts. That USB port is broken beyond repaid
I often have to switch between audio output from my speakers and my headset (P5Q mobo with integrated sound and Microsoft headset). I've already got it so that when my headset is plugged in, sound will be played through it, and if it isn't, sound will play through my speakers.
The problem is that if I have a game or similar program started while my headset is plugged in, if I unplug it, I will get no sound. Also, if I start the program with no headset, and plug it in, I get sound still through speakers.
Is there any way to do this?
This depends completely on both the application and sound card.
Generally speaking, applications can "request" sound on a certain device, (and give you the option to change devices).
Games on the other hand requests sound when they start running (through DirectX) and then keep playing through it. In some games you can restart the sound system by changing sound settings in-game, such as if the game offers 3d sound, or any sort of "advanced" effect, however generally speaking, volume alone does not do this.
The best alternative that is guaranteed to work is to get a speaker with a headset port as the moment you plug in a headset, the speakers will output to it. Unfortunately for you, I have never seen one with a USB headset socket.
If you are using Windows 7 (which your tags seem to indicate you are), this should work. Windows 7 adds a new feature to route the audio on the fly to a newly arriving device like a USB headset. Likewise, when you unplug the headset, the audio will re-route to the last device it was playing on.
If you want to manually move the audio, you can do so in the control panel. Here are instructions:
That's it. Audio will now route there immediately. Note that this is new to Windows 7 and won't work on Vista or XP.
i don't think there is a fix for this, the USB headset is a separate audio device, applications don't automatically switch audio devices if one becomes unavailable.
the only way is to restart the game or application.
To make your headset give sound, it is actually pretty easy. I have a USB headset, and so do you. Right Click on the volume icon
Make sure THE SPEAKERS have the default device. Cancel all of that out, then unplug your headset and wait about 30 seconds. Plug back in, and when you go back to that first page, your headset should be the new default device. :) Your welcome.