The Pre has an OMAP 3430 rated at 600MHz. There is a 720MHz version of the OMAP3430 available, but it is not in the Pre. There is a different OMAP chip which runs at 800MHz, again it is not in the Pre.

Running a 600MHz OMAP at 720MHz reduces the lifetime from 100K hours to 44K hours according to the manufacturer data-sheet. It is not known how much further running at 800MHz reduces the lifetime. Note that even when running the OMAP3430 at 600MHz, the operating point is referred to in the manufacturer data-sheet as "OPP5: Overdrive".

Note that going from 720MHz to 800MHz increases the core voltage by the same amount as going from 500MHz to 720MHz, so one might expect a similar reduction again, perhaps to ~20K hours, but that is pure conjecture as the data is not publicly available from the manufacturer.