I ordered some 3V Pro-minis by mistake and opened their packaging without knowing. The silk screened check boxes on the bottom side are not checked on the ones I haven't opened, so I have no clue about the other ones that have been mixed in with previous purchases.
Unlike the Nanos that have the regulated pin marked 5V, all the Pro-minis just show Vcc. Do I need to power these up and measure that regulated pin?
Yup - put voltage between vin/raw (markings are not consistent on clones) and ground, measure vcc.
If they use a crystal instead of a resonator (many clones do - crystal is better, because more accurate clock) you can read crystal frequency off top of crystal, which will tell you, too. Most resonators don't have the frequency clearly marked though (some do). And if they use a sot-223 reg, those have enough space for markings that they usually have the voltage clearly marked too.
Then, once you've figured it out, get out your nail polish (or steal your gf's) and mark the checkboxes on the back!!!
Parts markings are either illegible or part numbers, not values. But it was a good idea.
I think I'll just test the voltage on the regulated Vcc pin.