couple things to note:

MSI board has the option to do Vcore OFFSET, so you set VID to whatever you want (or is supported by your CPU) and then the "Vcore voltage" option starts from your VID and allows voltage levels above CPU VID value.
You can also control this with the AOD CPU Vcore slider (this is not the CPU VID slider).

So lets assume your VID=1.200V (CPU VID=28), then the Vcore setting starts at 1.200V (AUTO) and you can go up from there.

the "NB Voltage" item in the MSI BIOS is NOT for the CPU NB voltage rail but for the 790FX Chipset (which doesnt need any extra voltage because is the OVCK champ!). So there is usually no need to touch this item.

TLB bug is one thing and CPU / CPU NB clocking is another thing. Not directly connected. In order to OVCK the CPU NB you might need increase the voltage. Just like with CPU core.

And Phenom 9500 is set to 1.200V by default because that is the default voltage. MaxVID=1.2500V.