I'd have to check my notes, but I don't believe it would start at 10V. I had to start it at a higher voltage and then turn it down as it was running.
If I had to guess it's a limitation of the string design as opposed to the chip itself. The numbers Bitmain gave are likely accurate for those voltages, the S5 just won't get there. Hence why they removed the language in their thread that it could be run at 9V.
The best stable voltage I could get it to run was 11v.
Anything from 10.0v to 10.8v, the miner started but stopped after 10-30 minutes hashing.
I asked Yoshi from Bitmain if they could help understand why it failed, but got no answer on this specific subject.
Starting at 12v and lowering voltage down to 10.8v gave me the same results as starting at 10.8v: few minutes hashing, then stop.