Intel says that their "temperature target" number is the minimum temperature so actual TJMax can be slightly higher than 100C but it won't be lower. My best guess is that actual TJMax varies between 100C and 105C on many of the Core i7-900 series CPUs with core 0 being close to 100C, core 3 being close to 105C and the two center cores being somewhere in the middle. My theory is that Intel might deliberately offset TJMax slightly so all 4 cores don't reach the thermal throttling point at the exact same time. By offsetting TJMax, you get a more gradual decrease in computing power so it's less noticeable to a user.
The sensors that Intel uses are far from perfect so it's certainly possible that your sensors read a few degrees high. If you bought 10 different i7-920 D0 CPUs and mounted them one after another on the same board, it's not likely they are all going to read exactly the same. There will be some variation but Intel has never said how much variation should be expected.
The reported temperature coming from a batch of Core i7-920 CPUs would be very close together compared to the previous Core 2 45nm generation. Those crappy sensors were all over the place from one CPU to the next.
Send me a box of Core i7 CPUs so I can start testing this theory. :)
