Computer Interference when using Front Out

[Arctia]

Thanks for all the suggestion guys. I played around some more, I can definitely rule out that it's a defective sound card. Here are some "fun" things I discovered.

1. Even when I'm playing around in the BIOS, the problem exists. I move my mouse and I can hear screeching noise.

2. The power grid at my apartment is pure crap. I turned everything off, and plug'ed the power cord directly into the grid, OMG THE NOISE. Keep in mind that this is with THE POWER SWITCH AT THE BACK OF THE PSU AT OFF POSITION, ie the computer isn't even on. God, then I found some old surge protector and plugged it in, much better. There are still some noise, but much better. Stupid Dynex power cord, DON'T BUY FROM DYNEX.

3. It doesn't even have to be the sound card jack. In fact, exact same problem when I plug it into the integrated sound jack that's already disabled from the bios, same result. Just for fun, I literally taped the connector ON TOP OF MY CPU HEATSINK, exact same problem lol.


So either the power is really unclean, or my motherboard has serious grounding issues. I'm leaning towards the latter. Tomorrow I'm going to tape a wire from my CPU heatsink to ground, and we'll see what happens.

 

[ROBSCIX]

This changes things slightly.

 

[leeperry]

if you have a UPS, you could also try to remove it....actually I tried many things at once, can't tell which one did the trick for sure..

also, this is supposed to kill a hell lot of EMI/RFI(up to 43dB): Belkin SurgeMaster, 1-Way MasterCube with Tel/Fax: Amazon.co.uk: Electronics & Photo

http://www.apcmedia.com/salestools/A...3TSZ_R1_EN.pdf

 

[Arctia]

Power damper did nothing. Making an extra ground line did nothing.

At this point I think it must be the power supply or the motherboard, both I'm reluctant to change.

oh well, DAC time.

 

[FasterThanEver]

Quote:

Originally Posted by Arctia /img/forum/go_quote.gif Power damper did nothing. Making an extra ground line did nothing. At this point I think it must be the power supply or the motherboard, both I'm reluctant to change. oh well, DAC time.

A description of your computer would be quite relevant. If you bought the PC as a whole, the brand name and model would be informative. If you bought parts and assembled it yourself, what CPU chip, motherboard, power supply and case do you have?

Your problem seems quite severe and well beyond the normal experience. If you use an external DAC, you might consider a Toslink cable (optical) rather than a coax cable so that you get some electrical isolation between the PC and the DAC.

Bill

 

[Arctia]

Built it myself. EP45-DS3R motherboard, pcp&c 750W silencer. I took everything out of the case, sat the board on top of a card board box. Plugged the power supply in, without even flipping the switch at the back, still noise all over. I know the 24pin motherboard connector is missing a ground pin, but from what I've searched, it was intentional since there are enough grounds on all ATX compliant boards. It's currently using a Q9550, I suppose I could switch my old E8400 back in when I feel like experimenting more.

I only notice this if I plug the amp in. Can't hear any interference if I just plug in the headphone directly.

 

[somestranger26]

Bizarre ground loop maybe? Sounds like a DAC is the solution if it's not happening when your headphones are connected directly.

 

[Arctia]

okay it's DEFINITELY a grounding issue, I found a workaround YES!

You know how the prelude has 4 analog outs? Currently, the front jack is plugged into my amp. If I just leave that one plugged in, noise, lots of noise. By pure luck, I took the cable coming out of my amp's pre-amp slot, and plugged it into another out jack on the prelude. Surprise, noise cut in half. Before I could hear stuff when the amp's dial is set to 3, now I can't hear anything even when the volume dial is at 6.

Here's a diagram for better understanding. Anyone good with physics wanna tell me how the hell this works? http://img23.imageshack.us/img23/6927/diagramu.png

 

[leeperry]

if you check the last paragraph of the PDF I mentioned above, I'd say what you just explained matches.

you seem to have some funky "Inter-System Ground Noise" going on...tried to plug the amp and the PC on different outlets?

 

[Resonator]

Had the same issue last week end. Drove me completely nuts. Been unplugging and plugging every combination I could come up with. Started to run wires from ground to MOBO, case and other parts. Unplugged all fans. Moved PCI cards around. Took UPS offline. Did everything suggested in these forums. No changes.

I gave up after hours of messing around with this issue. Probably have a crappy MOBO. My older machine running XP was worse, but my newer Dell was also doing. Instead of hooking up the DAC (emu 0404 in this setup) via USB directly it is hooked up via TOSLINK only. Done. No more mouse movement or hearing the computer 'think'. Total silence. Woot.