It sounds like a grounding issue and is the reason why yours speakers or monitor are affected
I would suggest you...
Unplug it
Double check everything is connected correctly, especially power supply wires and power/reset wires are in the correct spot (use the motherboard manual for reference)
If you built it from scratch perhaps too much thermal grease was applied to the CPU causing conductivity issues
Also try plugging it into a different outlet or even take it to a buddies place and use their outlet
I have a power hungry portable A/C unit and only one outlet in my place uses a 30 amp fuse in the breaker box, the rest are 15 amp... so I can run the A/C 24/7 from the 30 amp outlet but if I use a 15 amp outlet it shuts off within about one hour. I also have a power hungry plasma TV from 2003 which I am currently using on a 15 amp outlet. My PC is hooked up to the same outlet as the TV too. The TV works fine but sometimes weird blue pixel ghosts appear all over or the brightness of the screen is compromised supposedly due to lack of power, no issues with my PC though. I was doing a tailpipe repair on my car the other day and I had to remove the muffler but I didn't realize there was a grounding strap attached from the muffler to the body so I ended up breaking it. The rear speakers in my car sounded fine before but now they sound so bad I am only using the front speakers for now.
My parents have a newer, bigger plasma TV than me and theirs actually came with one of these on the power cable.
https://www.amazon.ca/Ferrite-Core-Cord-Noise-Suppressor/dp/B0002MQGEKoh another thing is your power supply under powered maybe
idk just throwing out random suggestions because it's a strange intermittent issue
This post was edited by Mackenzie_1992 on Dec 8 2018 08:34am