There is no way the CUSL2-C supports a min. of 1.75V... a Coppermine 600 is like 1.65V and I think even upto 1.0GHz it is 1.70V (my 933 is)
where are you looking to see that it supports 1.75 minimum because it definitely should support less, the board is designed for the coppermine.. hence: (CUSL - CopperMine Solano chipset)
A TUSL2-C is basically the same mobo except it has Tualitin support, there may be a few other things, but thats the main difference between the 2.. it will definitely take a coppermine CPU or a celeron coppermine CPU.