I'm having issues with a static noise coming through my speakers.
The noise is in general quite quiet, and most of the time cannot be heard unless no other sound is playing through the speakers. It is a sort of sputtering static sound of medium pitch. I don't really know how to describe it better than that.
The noise gets louder when I do something on the pc, like for example scroll down a page, load a new page in my browser. It gets especially loud when I do anything intensive, like try and play a game like Skyrim for example.
There is no noise if I connect the speakers to my iphone and play music through there.
There is however a noise if I connect the speakers to my old laptop (which is connected to the same power source as my pc. The battery is broken so I can't disconnect it.)
There is much less noise when I connect to my GFs laptop which is unconnected to any power source. There is still a very faint noise but vastly more bearable.
Some info about my specs and what I've tried:
Running onboard sound from my motherboard. My headset is also run off of the onboard sound, and gets no static or noise whatsoever. I get the noise regardless of whether I plug the jack into front or back sockets.
I replaced the power cable to my pc, since it was running through a European to UK adaptor. No change.
I replaced the extension cable that my PC and speakers were running off. They are now all (PC, laptop, both speakers) plugged in to the same extension cable, which is plugged directly into the wall. No change.
The speakers are KRK Rokit 5's. I have two, both make the same static noise. They are connected to my pc via a standard red-black connector thing. I previously had a very old pair of speakers connected to my PC. They didn't have the constant static noise these ones do, but they did frequently make a beeping noise as if they were picking up morse code or something.
I opened up my pc to have a look and see if any cable was running near a fan. There is one that plugs into the motherboard that runs past the graphics card and the CPU fan. I moved it so that it should no longed be touching the CPU fan. However this has not fixed the problem. I don't see any way to get it to not run past the graphics card however.
All parts are less than one year old.
Options I'm considering:
New dedicated soundcard: I'm reluctant to do this since it is a fairly expensive option. Besides which, I get the sound on my laptop and I don't get any sound coming through my headset, which suggests it may be some other problem.
External sound card (something like this): I've heard these can be effective removing static from audio. Again, this is a fairly expensive option.
Replacing the black-red cable: Since the speakers seem fine through my ipod, I doubt the cable is at fault.
Replacing the speakers: Again, since the speakers seem fine through my ipod, and in general seem to have a very high sound quality, I doubt they are at fault. Plus returning them would be irritating.
Any suggestions would be much appreciated.