Yes, you can connect a 3-pin addressable RGB to a 4-pin addressable RGB on your motherboard.
Yes, you can connect a 3-pin addressable RGB to a 4-pin addressable RGB on your motherboard.
You're not allowed to use these connections. ARGB headers require 5V power with specific pins, while RGB headers need 12V and their own color pins. Matching an ARGB strip to a non-ARGB header will damage it. BPS Customs conducted video tests on this issue.