electronic noise from computer in stereo speakers

[desmondjim]

I recently completed an HTPC/media server build that is connected to my TV and stereo via HDMI to the TV and analog 1/8" to RCA to the stereo. I am getting a veriable high pitched electronic noise in the stereo speakers that seems to be tied into cpu/ hard drive usage. When the pc is idle there is no apparent noise, but when I task the pc to do something like type on the keyboard or copy files to the hard drive over the LAN I get noise. I unpluged the analog audio cable from the pre amp and I still get the same noise. I even turned off the pre amp with just the amp on and I am still getting the same sound.
I wonder if the PSU is contaminating the ac back though the rest of my system and the amp is picking it up and sending it to the speakers.
I would greatly appriciate any ideas of how to eliminate this noise, I cannot use the computer for it's intended purpose if I can't get it under control.

Build
Biostar Hi-Fi A85W motherboard
AMD A10-5800K CPU
Rosewill Hive 550 PSU
Crucial M4 128 ssd
4 Western Digital Green 3tb hds
Silverstone GD-08 case

Cheers,
Jim

[mlc]

Jim...

do a search on "coil whine" to get some ideas... could be psu, mobo or graphics related... due to components used.. Try disabling some of the power saving settings in the bios to see if that helps, and go from there.. (e.g. EIST, C1E)..

It wouldn't hurt to try plugging PC into a different outlet.. just to see if there is a change in behaivor as well...

Good Luck
Mike

[Deders]

pretty sure it's not coil wine, would be good to know what happens if it's plugged into a different outlet.

[denis280]

Originally Posted by desmondjim

1/8" to RCA to the stereo

is this a good quality wire.

[jolancer]

This isn't uncommon IMO for cheap components. iv ownd some myself that exhibited crosstalk. Its usually not an issue though since the interference noise isn't noticable once you start using the audio you cant hear the interfience anymore. If you are still hearing it excessivly i'd guess its because your amp or some other stereo component is sensitive to the interferince or miss adjusted (sorry im nota stereo guy) but i do know just like software amps if your settings or gain is outa wack, or your just MAXing everything you will invite more noise interferience.

you know how it goes, you get what you pay for. The interferience is from within your computer, cause the cheap onboard audio controller doesnt have any shielding or suppression from normal interferience.

perhaps try the digital output instead of the analog? and see if you get lucky... or get an aftermarket Audio card.. as long as its not a cheap peace of garbage i'd imagine any would have better noise isolation then the one built into your board.

....or i guess you could just lower the volume a tad, your neughbors may appreciate it to

[Deders]

I think he's saying that the noise happens even when the computer isn't connected to the amp

[desmondjim]

Thanks for the tips. I do have a high quality analog cable that is shielded, but the sound it there even if the cable is gone. I will have to get a long extension cord to find another plug that is not on the same circuit as this one. I will try that when I get home. I poked around the BIOS last night but could not find EIST or C1E I'll research these on the Biostare site. Thanks for the suggestions.

[desmondjim]

I found the problem! There was a ground loop caused by the incoming coax to the cable box that was in turn connected to the pre amp with rca cable. The noise from the pc must have been riding on the ground loop, when I unplugged the coax in to the box the noise stopped. I then added in an inline isolation transformer that I had to the coax cable right at the cable box and that solved the problem for good!

[denis280]

Originally Posted by desmondjim

I found the problem! There was a ground loop caused by the incoming coax to the cable box that was in turn connected to the pre amp with rca cable. The noise from the pc must have been riding on the ground loop, when I unplugged the coax in to the box the noise stopped. I then added in an inline isolation transformer that I had to the coax cable right at the cable box and that solved the problem for good!

Great