Your post is a bit light on the details - but crashing is most likely due to instability. Have you:
1. Tried disabling EXPO and attempting to replicate it?
2. Tested memory stability with EXPO enabled?
I am not here for the crashing or instability issue but rather the annoyance of the audio being crackly after restarting. It does it occasionally after a normal restart as well. There really aren't any details I can give beyond that. If the system blue screens for any reason or hard resets for any reason or occasionally when normally rebooted the audio ends up in a state where its crackly until rebooted once more.
What makes you sure the two are not intrinsically related? Removing overclocking or finding the route of instability is troubleshooting 101.
Because it doesn't happen any other time only a crash or a reboot causes it. Even on completely default settings an occasional normal reboot causes it or if the GPU driver crashes the system. You can also trigger it by just pressing the reset button while the system is booted. The issue follows the board and not any other component.
But your system shouldn't be crashing. The board is just an interconnect, you need to establish why the system is unstable, or else you'll just send people such as myself up the garden path trying to help you. Buffer underrun issues can be linked to such things.
Have you tried either updating or rolling back the Realtek drivers?
Have you ran any stress tests at all?
The board is not just an interconnect, it has firmware for the audio and its been updated before for audio crackling but was for SPDIF. There IS an audio firmware issue regardless of what is causing my system to crash. Like I said, even when the system is 100% stable if you simply reboot it or press the reset button, the audio ends up in that state, it doesn't always do it 100% of the time but it does occasionally. The fact that it has crashed is irrelevant in this case as that is simply how I discovered the issue and a stable system experience it too.
At what point do you assume the system is 100% stable? Because it sounds like the complete opposite.
The board is an interconnect in as far as to say if the system is crashing and causing buffer underrun issues, there will be a reason.
Have you tried running a DPC latency checker?
Get your system stable first, and reevaluate the problem.
If you're not willing to evaluate this you'll likely have to go back to deliberating with yourself.
I don't come and post here unless I have exhausted all other troubleshooting steps. Right now, my system is default settings and 100% stable as stress tested for 24 hours with zero memory errors or crashes or instability of any kind; and if I run a windows update or reboot the system or press the reset button I will be able to reproduce the issue at least 1 out of 10 times. DPC latency is also perfect even when the issue is present it all checks out fine which is why I am lead to assume it's a firmware issue and nothing else. I could run a full stress test with the audio in that state and it all checks out fine.
There we go, that would have been useful instead of the singular sentence given in the OP 😁
Can you list:
1. All devices connected to the system USB or otherwise, inc speakers
2. Upload Dxdiag file
3. Confirm whether system defaults includes no EXPO & is complete Optimised Defaults.
4. Which Realtek driver versions you've tried.
I do have to ask, though - why even mention the crashing at all if 100% stable? Is this with EXPO applied?