So i tried your boards with hexmine in win7, tried all the combinations got 42gh with one board, 77ghs with two, 91gh with three, 101gh with foor
Do you have Hex16B or Hex16A2 (Hex16C)?
This is the Hex16A2 (Hex16C) thread and 4x 24GH would be 96GH+ so 101 GH seems normal.
If they are Hex16B don't run them all on the same length of wire because you will be using the same PSU rail.