google search temp + issues + E8400 47,100 hits. Seems every brand has problems. The Lenovo thing is what caught me eye and made me link to get away from so much speculation that has no real answers with the newer stuffs.

anna99, the temp probs in the E8400 are stuffed. The Coolest (the guy who makes coretemp) reports that according to Intels spec, his program is reading the temps correctly. In other words, coretemp is reading what the cpu is telling it. Basically the blame gose to intel because they stuffed up and now the temp probes don't work. Case and point, my E8400. According to coretemp, one core is locked at 43c, the other at 51c. They will not read any lower than this, ever... Once the temp moves above these values its starts to rise, but other report completely frozen probs (sometimes just reading 7c!). My motherboard reports 34c on the cpu all the time, i have never seen it move off this value (this may be fixed in future bios though).

Lenovo, the major laptop vendor, has sent back all thier E8xxx cpus because of "issues with temperature sensors" (i saw this in another thread here, so i have no referance, srry).

So basically we are stuck. I personaly choose to beleve my reported temps(when they move), but there is no eveidance pointing to the fact i should. In short, you are not alone. Every single E8x00 seems to have these issues. I think it requires a new stepping to fix myself, so i don't think it will ever change. Lets hope i'm wrong.