Vista - Humming through monitor speakers.

Any help with this greatly appreciated.

I recently started to use the monitor speakers - previously had the monitor volume turned right down.

There is an annoying medium-high pitched hum thru. the speakers.

The volume of the hum varies with the volume on the monitor, not the volume settings on Vista.

Detaching the 3.5mm sound lead ( DVI lead attached )reduces the hum considerably.

Detaching the DVI lead (sound lead attached ) removes the hum.

Using VGA lead makes no difference.

Have tried different sound drivers, different video drivers, reinstalled the o/s - makes no difference.

As the hum seems to be travelling down the DVI/VGA lead,
tried a different graphics card ( with passive heatsink - no fan ) - makes no difference.

Took the side off the pc and can just discern the same hum if I get my ear in the right place - from inside the pc.

Detached the rear fan - no difference.

Detached the mobo fan - no difference.

The only thing left is the psu - could the fan noise/vibration be traveling via the graphics card to the monitor ?

If so, any ideas how to stop it ?

Thanks

SIW2

Could be a ground loop problem. I really don't know.

Hi SIW2,

If you have another PC (or access to one), try attaching the monitor to that instead and see whether or not you get the same problem. If the problem remains, it is most likely to be a monitor fault, probably with the internal electronics. However, many problems like this are quite simple to solve, mainly through the things that we overlook. Try a different audio lead. In addition, to remove the possibility of a ground loop problem, use a multi-socketed extension lead to plug your PC and monitor in so that they are only connected to the one wall socket.

Hi Dwarf,

Thanks for your response. Have already tried the things you suggest, except connecting the monitor to another pc. I have been asking around for a few days , but the only machines I can get access to are laptops , or a mac - none of them will connect to the monitor.

Since it is possible to hear the sound from inside the pc, fairly sure it's not the monitor. Very hard to pin down where it's coming from as it is like a distant mosquito - till I attach the monitor, when it is amplified - like a mosquito inches away.

The sound does not come through the monitor if the DVI or VGA lead is disconnected.

Any more ideas welcome.

Thanks

SIW2

Hi SIW2,

You stated that you had recently begun to use your monitor speakers. If you had used other speakers prior to this, did you have this problem before? Roughly, whereabouts in your PC can you hear this humming noise?
With many monitors, if there is no video signal then the monitor will go into standby mode, thus also turning off the audio speakers.
Restart your PC and go into your BIOS. Select the 'System Health' page and monitor the values. Do any of the voltage lines fluctuate more than normal? Can you still hear the hum, either through your monitor speakers or from inside the PC itself? Open and close your optical drive. Does this make any difference? If you have more than one, repeat. Disconnect the power cables from your drive and repeat the monitoring test. Repeat this test, connecting one drive at a time (always power down and disconnect from supply before connecting or disconnecting cables). Do you notice any changes, and if so, at which point?
It could be a PSU filtering problem, in which case you will need a new PSU even though your existing PSU seems to work normally otherwise.