Hello Dimplex, you processor is working under specification. According to the following link the T-case of this chip is 72.6 C. ARK | Intel® Core™ i5-2400 Processor (6M Cache, up to 3.40 GHz)
Also, Intel doesn’t validate 3rd party tools as per diagnosing our products. I invite you running the Intel® Processor Diagnostics Tool to see if it shows up any error http://www.intel.com/support/processors/sb/CS-031726.htm
Yes, but I'm wondering about IDLE temps (~10% usage, actually).
HWMonitor says: "Package" 37C.
For 10% usage that is too much.
I have 1 140mm fan for outtake and 2 140mm for intake, so I don't see any airflow problems.