Batch 16 is when the autotune was introduced so any after that are autotune only.

As I've said earlier on here IMHO Bitmain forced autotune boost the # of chips they can actually use instead of scrapping under performers. I have a batch 18 with wildly different speeds per-board but in total the miner runs at advertised 11 TH/s. Barely. My guess is they stuff the boards then test to get speed ranges for binning. After that they pick combinations of fast/slow boards to make the miner reach target speed.

ref that b18 miner to the b23 I just got -- on this newest one all boards are running 649.7 to 649.9 MHz to produce 14.129 THs. Obviously the b23 boards were cherry-picked for them.