I’ll be running my amd framework mainboard in the coolermaster case, as a headless home linux server/nas, and trying to decide on which usb-pd power supply to use for it - but to answer that, I need to know:
We have only the Intel mainboards to go on, data is still coming in about the AMD mainboards.
But - on the Intel mainboards - in standalone usage without a battery, the recommendation is a 100W USB PD power supply. In heavy use while also charging, the mainboard will draw from the battery at times. Without a battery to draw peak power from, 100W is better.
However NAS/server use may not push it that far, ever, and even if it did, it’ll still operate with 65W, maybe not with full turbo.
As for grounding, grounded is always better but it’s not the end of the world if it’s ungrounded. A metal case may give off a tickle with an ungrounded power supply, but that’s about it. The Cooler Master case is plastic so it’s an insulator, so you won’t get anything off the case. It could put a little charge on the USB grounds though. If you then plug in a powered USB device powered by a grounded power supply you might create a ground loop. That may not affect anything on a NAS though, usually it’s only speakers that would be affected.