Question Windows 10 Update 2004 messing with microphone and CPU lag

[triuly]

So basically, a few months ago, I reprioritized a game from High priority to Normal priority in Task Manager. This is the only thing that I can think of that would lead to systemwide lag and my CPU fan going crazy, ramping up and down for no reason. I tried basically everything that I and my friends could think of, with messing with different settings in BIOS, reseating fan and processor and reapplying thermal paste, and power plans and everything. So, as my obvious last resort, I reinstalled Windows. Now this problem has persisted through the reinstall, bringing me to the conclusion that this might be a hardware issue, even though tons of stress tests show no problem with hardware. This brings me to my second concern, with reinstalling Windows. I unknowingly installed it in Legacy-Bios mode instead of UEFI, and I read about using MBR2GPT to change from MBR to GPT, which then lets me (to the best of my knowledge) change from BIOS to UEFI in firmware. My last problem is with what I'm going to assume is with the new Windows Feature Update 2004. Before I reinstalled Windows I installed the update 2004 to see if it would fix my lag problem (which surprise surprise it didn't), and this update messed with my webcam's microphone (I don't have any other mic and I use earbuds so no split cord), and made me sound robotic and distorted in any application I tested with my mic, where it be OBS or Discord or Audacity, or anything else. I reinstalled the drivers for the webcam and disabled and re-enabled the HD Audio Controller in my BIOS. I also tested the microphone with my brother's computer, and there was no problem with it, showing it isn't the webcam's problem and a software problem.

To summarize:

Problem #1
Systemwide lag cause by reprioritizing a game, nothing I can think of fixes it, clean reinstall did not fix. The best way I can explain it is like breaking a pot, and gluing it back together, because I cannot seem to reverse the damage done but only reduce it by turning things on like XMP which my computer ran fine before I even knew what it was.

Problem/Concern #2
Reinstalled Windows in Legacy-BIOS instead of UEFI, changed to UEFI using MBR2GPT and was wondering if it's safe to do this.

Problem #3
Robotic sounding mic after Windows 10 update 2004, most likely not a hardware problem, tried reinstalling drivers, cannot test rolling back to previous Windows 10 version because I just reinstalled Windows 10 fresh.

If you made it this far thank you so much for reading and hopefully someone can help me with any of these problems I'm having

 

[Nahuelic12]

Hello, this is kind of an old post but anyways:
You should not install Windows in any other form of BIOS other than UEFI in this days, if your pc is from the last 6 years, you will probably bump with a message like this while booting:

View: https://www.youtube.com/watch?v=_r51Ce-b7Ds

This error will literally be solve only by formatting your bootable USB to UEFI, so that's on that.

In concerns to your pc performance after update, one rule we always follow in this forums is to share our pc specs detailed in the post so we can know with what kind of hardware we are dealing with. Be sure to follow this rule the next time. For now, i will suppose you are working with hardware from the last 6 years at least. Considering this, if your pc is dealing with unknown issues and there seems to be no fix by reinstalling your drivers or updating them (i recommend Steam's version of Driver Booster for this task, although you can always check for your hardware manufacturer web page for more details into the drivers and downloads), the safe way to fix this problems and test results would be to rollback the Windows version (the most stable version of Windows 10 i know is Windows 10 Ver. 1909 build 18363.10).

If you rollback to that version and everything works fine, it is most likely that your pc isn't ready for the 2004 update and you should wait more time for Microsoft to fix bugs in it, while this version is universally stable and works know, unfortunately it wasn't the case for you. Please, answers this post with your results so everyone can have more insight into this issue later on.
I hope this post finds you well and your problems end up resolved.