I've got a few strange symptoms on a machine I built:
- The machine won't boot (sometimes) with certain USB thumb drives plugged into USB ports; disconnecting the front panel USB/firewire/audio seems to have helped, but I'm not sure...
- On-board audio has noticeable static/hum; it seems to only happen when ethernet is plugged in. I bought a Sound Blaster X-Fi XtremeGamer (wanted a nicer sound card anyway) and that seems to have resolved this issue, but...
- ...the new sound card occasionally loses track of the speaker jack and gives me only SPDIF out (and occasionally an "internal aux" output shows up in the available outputs list). From what I understand, modern cards often automatically switch based on measured resistence
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?