Tjunctioin: What is it and how hot is too hot?

I am prime testing my OC of my E6600, and in Core Temp it lists a temp for "TJunction" at 85C. What is the TJunction and is 85C hot?

My cores are fine, 44C and 43C each, but I am not sure what Tjunction is.

Also, at what FSB should I start considering putting a watercooling block on my northbridge? My CPU is watercooled, but my 680i MCP currently only has it's heat pipe and the stock fan meant for watercooled systems. I am afraid to push the FSB too far above 400mhz without putting a block on the MCP to keep it chilly.

My current stable on my E6600 is FSB 400x9, 3600mhz, memory is running at 400mhz 1:1 ratio, 4-4-4-12. I can run at 3600mhz with the memory at 500mhz, but the timings are a little too loose for my liking.

That's normal, don't worry about it. I think that sensor is not important. I think it's suppose to be air temp. Not sure. Same thing on my e6600 though. Nothing to worry about. Just worry about core temps.