I have two P5S-VM boards and both of them cannot boot at 2.0V. They use HIP6008BCB as voltage controller and here is the voltage selection guide from HIP6008BCB's datasheet:

And here is the voltage selection guide from P5S-VM's manual:

By comparing the two it seems that:
1, P5S-VM only uses VID0~3;
2, Jumper 1-2 on manual = 0 on datasheet, jumper 2-3 on manual = 1 on datasheet;
3, VID4 is set to 1 on P5S-VM.

If the above assumptions are true, we can conclude that the 2.0V setting on P5S-VM will result in 0V output.
It's easy to verify the assumptions. By pulling VID4 (pin 8 on the chip) to ground the board boots at 2.0V and lower.
It's a shame that ASUS omitted the fifth jumper and closed the portal to the low voltage world, and it's a bigger shame that they made us boot 2.0V CPUs with no voltage at all. 😵