I'm using the x64 version to test my E8400 C0 on Windows Vista x64 and I was wondering what is considered the max safe temperature. I'm using RealTemp to monitor the temp.
In other words, when should I backdown and/or get worried eh?
When delta to Tjmax = 0 you should start to worry. See the setting options and refer to the programs documentation / web site information.
For day to day operation most of us like to keep about 20C Delta to Tjunction when running your normal applications/game, or better. For your cpu this is a coretemp of 80C.
Per Intel - TjMax values:
45nm Desktop Dual-Core Processors
Intel Core 2 Duo processor E8000 and E7000 series - 100°C
The latest version of Core Temp should have Tjmax already set to the proper value. Look at the value of Tjmax listed by the program, and only change it if it isn't set to 100C.