Can I run Gemma 4 12B it on GeForce RTX 3080 10GB?

This one is close. The answer rests on a file size we calculated from the parameter count rather than measured. A 10% error in that size changes the verdict, so treat it as a maybe and test before you buy.

7.6 GB of weights, plus 2.2 GB for the software that runs it and the smallest conversation it can hold, comes to 9.8 GB against the 9.2 GB this 10 GB device leaves free.