100 C is too hot and above Intel's max rating according to
this page.
Did you have another OS on this hardware before Windows 7? What CPU temperature did you see with that OS?
Check that all your fans are in fact spinning, especially the fan on the CPU cooler. Fans can get jammed or unplugged. Make sure that hot air is actually being exhausted from the case. A failed CPU fan on a small heatsink can cause a large temperature rise. If your heatsink is
large, and the other fans are working, passive cooling would probably keep the CPU lower than 100 C even with a failed CPU fan.
You could try downloading
SpeedFan and see if it reports different temperatures. I'm not familiar with Real Temp and have seen spurious data from temperature reporting programs in the past. Also, reboot and enter Setup. Setup should report temperatures on some setting page.
If you turn the computer off and place your fingers near the CPU, you should feel a lot of heat if 100 C is the actual temperature. But be careful, 100 C is scalding hot and you would burn your finger if you touched something that hot.
If this is a newly installed system and you confirm the temperature report, thermal paste and heatsink mounting is where I would look. Maybe one of the heatsink mounting brackets is loose? Any air gap between the CPU and the heatsink caused by thermal paste separation or improper tightening could easily cause CPU overheating in a
very short time.
Guy