First off, that's an excellent overclock on your chip. What are you using to cool it, and what are you using to measure voltage?
Secondly, the comparison between C8H and Aorus Master is kind of a wash. They're both excellent boards. Aorus Master has some . . . issues with onboard sound and fan behavior for some users. I haven't run into any problems since I'm actually using my video card for sound (Radeon VII) and I keep all my case fans on mobo headers set to max (meaning I don't have any PWM behavior problems). I don't own a C8H but I've heard a few gripes over Asus hiding some fan settings in the UEFI that theoretically could be exposed.
Thanks. I have been very surprised by my CH VI Extreme X370 mobo. I'm using a Kraken X72 360mm AIO, with Kingpin KPx thermal paste. I'm just using Ryzen Master, HWMonitor and CPUz. The funny thing is when I first OC'd it, I was able to pretty easily get it all the way up to 4450mhz at 1.26875v. I actually got it to run at 4475mhz for a while, but it was not stable enough to complete three runs on CB R20. So settled on 4450mhz at 1.26875v, and was able to easily run R15, R20 and other benches on multiple runs with no problems.
But then I made the mistake I always make (LOL), and instead of being satisfied, tried to push it to see how far it would go, and of course crashed the system. And now I can't get it to repeat that record, even though I wrote down all of my settings and used the same ones. So right now it is OC'd to 4425mhz at 1.26875v.
And yes, the fact that those two boards are so close is what has me pulling my hair out trying to decide which one to go with. I've heard a lot of people complaining about getting dead boards or boards that died in the first month from Gigabyte. But I also know a lot of reviewers complain to get what they want, and aren't necessarily reporting the truth. So I am guessing it will all come down to who gives the best Black Friday deal. Do you have any better Black Friday shopping sites than Amazon, Newegg or Micro Center???