Problem with noisy audio on computer

Good way to test.

Find a friend with a Mac, which has zero noise electronics.

Test all your gear - cable, mics, etc... - on the Mac, then move one piece of gear at a time back to your PC + retest.

Likely this will surface out some sort of flakey gear.

From the audio samples you dropped, this sounds like your machine or SoundBlaster card.

Likely I'll catch flack about saying this next bit...

I use to use Windows + various sound cards. Every single variation produced oddball artifacts, like the audio samples you dropped.

When I switched over to using Macs, all issues disappeared instantly... so...

You can spend hours of your life replacing motherboards + sound cards, or just pickup a cheap used or new Mac.

If you generate your income producing audio/video content (I do), then likely best to go with a Mac + be done with your artifact problems.

Tip: If you purchase a new Mac, apply for a Barclay credit card at checkout, for 18 months zero interest financing.

I am going to second what David says about testing on known good equipment right up to the "buy a mac" advice :)

Often, PC power supplies can be poorly regulated or can be badly isolated. This can lead to noisy recordings (assuming everything else checks out OK). The kind of noise on the recordings you quote does sound like it could be interference of this kind, so check out the components in your PC and see if the power supply could be the cause.

Also, whilst they are not 100% guaranteed to reduce noise, are you using ferrite beads on links between sensitive equipment. That can also help reduce noise, on occasion.

Thank you for the information.  I work for a non-profit educational institution and we are just streaming our chapels and conferences for free, so it is more of an annoyance than any sort of income generation issue.  I did not experience these exact audio issues on my previous machine and it is actually all three of the ways that I indicated that it is causing a problem (Soundblaster, mic in, and blackmagic), so I was more looking at whether someone knows if these sorts of issues are caused by a particular component more often than not.  So, yes, I am looking at spending hours of my life replacing certain components.  This is a brand new build, so I cannot replace it with a Mac as I have no budget to spend that much money.

Yep.

If your income lives or dies based on your audio/video quality...

Purchase a Mac + invest your time generating new content, rather than debugging ghostly audio artifacts.

The way that we are currently set up is to run a 1/4 inch from AUX on a sound board directly to the computer via either RCA or 1/8 inch. Thank you for the information about, possibly, the power supply.  I may invest in a different case and power supply combo or else just simply test with a different power supply.

In the crazy idea category: Have you tried moving the computer to a different location to see if the noise goes away? Might be something in the vicinity of the computer adding noise though a poorly shielded cable or connection.

As for moving to a Mac, I agree as well, and it does not have to be a new one. Used Macs a few years old can be bought at very reasonable prices

Just occurred to me. You might also try connecting your computer to a UPS to completely isolate your computer from your electrical system.

Likely this won't work + if you're working with audio/video production, you best have a UPS anyway, so try this first.

test if it happens with an other pc too, to be sure the pc is is the problem
you may post the specs, or model of the pc for better help

It is a custom build computer.
It has:
AMD FX-8300 Processor
Arctic Freezer A11 CPU Cooler
Gigabyte 78LMT-USB3 R2 Motherboard
Blackmagic Design Intensity Pro 4K
16 GB Memory

It has a couple case fans, also.

And the power supply is?

Thermaltake Smart 500w 80 Plus

I don't think that is specifically an isolated power supply. A while ago, I read about earth continuity as well. I believe that continuity loops can cause audio issues, so maybe see if that is causing the issue for you.

first  - can you confirm the pc is grounded as it should? continuity between case and earth?

How would I guarantee that the case is grounded properly?

Depends on the country you are in, I imagine, You can create your own earth wire and connect it to the case. In the UK, PC power supplies are usually earthed. The fact that the supply is then fitted to the case usually ensures continuity, but you can check and make a connection if continuity is not present (which is unlikely).

you measure it with an ohm meter, from pc to a known good ground - should be 0 ohm

Alright, this is definitely an issue between the computer and the sound board.  If I plug my phone into my computer and play music there is no problem.  If I run the sound through the sound board into my computer then there is a loud noise.  The noise level does not change at all by changing the volume on the output (in essence putting my headphone level at 0 and 100 there is no change in the volume of the noise) and even with all faders on the sound board muted there is still the same noise.

Thank you all for your input.  The issue ended up being that when the sound card was installed Realtek HD Audio Manager was also installed, which then added the gain to the input causing the noises to come without any intervention by me.  Once I got that program/service out of the machine it started back to normal operations.