3.8 is doable on almost all R7 chips. You likely can hit 3.6-3.7 on stock voltage with the 1700, I know mine does 3.6 at stock voltage. Getting to 3.9 is doable for almost all 1700X's from what I've seen and most 1700's can, mine included. I think I got mine to do 4.0 alright actually. Need to retest.