Computer/Electronic/AudiophileFilter: I just finished my first build of a computer. When I plug in my computer's onboard sound into my receiver through the standard 3.5mm audio jack and output to two KRK monitors and a sub, I get screeching/scrambling from the speakers that drives me nuts. It basically sounds like I can hear my processor. This doesn't happen with headphones. Lots more inside.
So I just finished my first custom-built computer, and now I run into this annoying problem near the end of it all that has me stumped. After about 36 straight hours of reading instructions and carefully wiring and setting everything up, I run into this audio problem with my onboard sound.
What I have is a Denon AVR-391 receiver, two KRK Rokit 5 studio monitors, and a PolkAudio PSW10 10" subwoofer. On my previous computer (OptiPlex 745, also onboard sound, no problems there), and all other devices I wanted to listen to on this setup, I would just hook up through a 3.5mm-to-2 RCA male jacks into the DVD audio inputs on the receiver and listen away. Well, this computer doesn't seem to like the setup.
I can hear clean, correct audio if I connect my iPod or laptop to the 3.5mm audio cable, which goes to the receiver as an input and outputs to the two KRK monitors and the subwoofer. So by that success, if I connect the motherboard's onboard line-out (green connection) to the same 3.5mm audio cable, I get a screeching/scrambling sound through the KRK monitors. All I can say about the sound is that it sounds like my processor working. If I open a program, I hear the screeching drop slightly, then pick back up when the program is open.
So I then try to send the motherboard's onboard line-out connection to a pair of old Juster speakers
and don't hear the screeching at all. Also, if I plug in a pair of headphones, the screeching doesn't exist there either. I've also tried directly connecting the motherboard's line-out directly to the KRK monitor without the receiver in the middle, and it still exists. So it looks like the onboard audio from the motherboard doesn't like any type of connection to the KRK monitors.
I've tried connecting the computer to a different outlet entirely, and one of the monitors on a totally different outlet on the other side of the room to see if there's too much power, or a grounding issue or something going on, but the problem still exists.
I've tried disabling all other audio devices through Windows, as well as all recording/line-in devices, but nothing helps. I've also tried disabling some things in the BIOS such as onboard sound all together on boot up, but that doesn't do anything either. It seems the sound begins as soon as the "Starting Windows..." logo appears on boot-up. Another thing I tried was connecting the 3.5mm audio cable to the front panel's headphone-out and the problem exists there too.
Also, all devices are connected to a 6-outlet Tripp Lite surge strip, and that is connected to a 3-pronged outlet. There are no adapters going on here.
I hate getting into these pickles when I take on a project like this. I've been thinking about buying an S/PDIF cable
and using that as the connection from the onboard sound to the receiver seeing if maybe that would help because it's a digital (?) connection, as opposed to the analog (?) connection of the 3.5mm jack. If that doesn't work, I've also thought about just buying a dedicated sound card such as the ASUS XONAR_DX
and seeing if I can get away from the onboard audio problem altogether.
I hope this is a common thing with onboard audio and studio monitor speakers (or any speakers), because I really don't want to rip apart the computer again and send the motherboard back. I'm sure the motherboard is okay anyway because everything else seems to be working perfectly. The processor, all RAM, SSD, etc. work flawlessly.
Does anyone have any insight or reasoning as to why this is happening, and do you think my last two options could be problem-solvers? I would really appreciate the help anyone has to offer.