Maximum temperatures

what is the maximum temperature you can get safely with a E6300 when monitoring them with TAT?

I don't know, but I personally wouldn't go over 75°, if you're talking about being safe...

It's a dark art. Everyone is guessing (nothing official from Intel), as no one has fried a E6300 yet. I run my E6300 @ 3.36ghz, 66C on Orthos Small FFT, following the almighty Core 2 temperature guide. Also, use CoreTemp to monitor temperature. TAT can be off as it's not designed for Core 2 CPUs. They throttle ~80C and shutdown at 85C. You don't want to go even remotely close to 80C.
http://www.tomshardware.com/forum/221745-29-core-temperature-guide