That doesn't surprise me. I sent my GE66 Raider in for two RMAs and they failed to solve both times. The warranty ran out before I could execute the third RMA (due to grad school) - and when I tried to set up the third one, an MSI customer support manager accused me of lying, even when I pointed him to this thread. They also managed to dent the top despite me sending in original packing material both times -nice.
However, all is not lost. I have found there's a way to fix this:
1. Disconnect your computer from the Internet.
2. Follow the instructions at the following link, which will prevent Windows Update from reinstalling the Realtek audio driver:
Prevent Windows Update from Updating Specific Device Driver | Tutorials (tenforums.com) . You do NOT want to turn off all driver updates, just this specific one.
3. Uninstall the Realtek audio driver from Apps, then reboot. After reboot, go to Device Manager and make sure it's no longer listed. If it is, uninstall from Device Manager and reboot again. (You may also need to uninstall directly from Device Manager if it was never listed as an App.) If a generic "High Definition Audio Driver" is already installed, don't touch it, and go to step 5.
4. After reboot, Windows probably installed a generic "High Definition Audio Driver", and you should have sound. Check Device Manager and make sure it's listed. If it is, you're good - you can reconnect to the Internet then run Windows Update to make sure all is well. You may get a weird Windows Update error due to what you did in step 2 but this should clear up if you run it again. If it's not listed yet or you don't have sound yet, reboot again while still disconnected from the internet. If that fails, reboot after reconnecting.
5. If you're still having trouble, try uninstalling Nahimic also. I did in step 3, so I don't know if it's part of the problem or not.
The root problem is that the audio hardware in the GE66 Raider is incompatible with Realtek audio drivers. And, despite what other posts in this thread state, I found ALL Realtek audio drivers - the one Windows Update installs, both of the ones available from the GE66 section of MSI's Support site, every Realtek driver linked to or mentioned in this thread, and multiple drivers both older and newer than all of the above - have the problem. The only solution is to uninstall the Realtek driver, then prevent it from reinstalling. The generic Microsoft driver isn't as good - sounds won't be quite as crisp or nuanced - but at least you won't have volume throttling anymore! Hopefully, some day someone can figure out what causes the incompatibility, or a Realtek driver update will fix it. But I'm not holding my breath.
EDIT: It's possible that non-official Realtek drivers might solve the issue, but I didn't try any of those.
EDIT 2: The person below me said they found it was a speaker problem. While that's possible, I'll note that my speakers were swapped during one of the RMAs and it did no good. It's possible though that I just got a second set of defective speakers.