As Markfw said, I ended up with the Fatal1ty X370 Gaming-ITX/ac over the Fatal1ty B350 Gaming-ITX/ac, Gigabyte GA-AB350N-Gaming WIFI, or Biostar ITX boards. I skipped the Gigabyte due some funky connector layouts as well as potential voltage regulation issues and the Biostar I felt wouldn't have quite the BIOS polish that I was used to (plus even if this a bias on my part it just feels lower end). This left it between the two ASRock boards While the limitations between the X370 and B350 chipsets were clear in a general sense they weren't clear in this particular ITX context. From what I read, there was a lot of speculation prior to release that the B350 board might have some sort of OCing limitations such as limited access to BIOS features or similar. Because I was a day-1 adopter, I made a snap decision before it went out of stock (this was also when boards were still having stock issues and I wasn't sure how long it would take to come back around). Turns out the only difference is PCI-E bifurcation and a faster Wifi card, neither of which I care about for this build. In general on all of these ITX boards VRM heat is an issue, which is partially why I went with an AIO rather than air cooler. I was hoping with how small my case is some of the air blowing inward from the AIO would help with the VRM cooling. Even still, the VRM seems to run about 10C higher than whatever my CPU is at pretty consistently.