My OC is stable at 4.8GHz with 1.392 max vcore. I spent some time during the update to 10.8.5 getting sleep working, and installed the mac mini 6,2 system definition.
Using that sysdef alone and with "generate cstates" and "pstates" in the boot.plist leads my system to max out at 3.4 GHz.
Putting an SSDT into /extra/ lets the system go up to 4.8, but the max voltage during normal use is 3.80. This is insufficient, however, and the system crashes.
Any suggestions are welcome.
EDIT: remaking the SSDT solved the issue. It might have been made while I was still on macpro 3,1, or because I had altered the TDP parameter.