I use AMD OVerDrive to enable TLB caching (and something else too ) - its the magic button in AOD right hand side corner (in 2.0.11 version, that will be out soon!).
it will not be an issue I will ever see in daily use (games, benchmarks, web-browsing, email etc).

as I mentioned earlier its not an issue that has anything to do with Overclocking, its not like you OVCK your NB/L3/CPU and then you suddenly get this issue. It happens in very specific conditions and regardless of clocks.

If your system hang when overclocking it just means that you reached the limit (need more cooling, better settings, more volts etc to go higher).

btw, as far as NB clocks (and L3 clocks) go: more cooling, more volts - thats how it goes higher.

KTE, do you remember what settings you used (in the BIOS) to get that "3.1GHz NB clock"? I strongly believe that its a misreading in CPU-Z