Geforce RTX 308 Ti mining speed only 66Mhz instead of 100Mhz

[grunsel00]

Any advice would be appreciated.

[scientificthe]

First, I assume you mean MH/s vs MHZ. Second, the max MH/s you can achieve is 88-95 range. You should be using trex miner and you likely need to update your vbios.
Here is a good video to use as a guide:

BIOS UPDATE for 3080 Ti Ethereum LHR Power Lock Issue 74mh/s to 91mh/s