Use a program called Real Temp, its the only program I've found that actually shows the right temps. My Bios shows something like 45c at idle, Core Temp shows 41c at idle, Everrest shows 41c at idle, HWmonitor shows 41c at idle. Real Temp will show at 31c idle. It seems like for the e8400 most programs have the wrong TJMax, they have it set for 105 when it should be 95. Real Temp is the only program i know of that has the correct TJmax. So basically subtract 10c from any other program besides Real Temp and you have an approximate temp. I wouldn't go by the BIOS since it seems to be way off what all the temp monitoring programs say, for me atleast with an Asus P5Q-Deluxe.
These temps are with a lapped Thermalright Ultra 120 Extreme with OCZ Freeze TIM. Ambient temps this summer are usually like 28-32c. No air conditioning 🙁. Right now it's about 21c since there was just a storm and it got cool. Idle is 31c, full load through Prime95 is 36c. This is at the stock 3.0ghz.
I think anyone who returned these CPUs pretty much should not be overclocking. How hard is it to open up google and research the issue and find out that it's just the programs and BIOSes are not correctly reading the sensors because they're configured for 65nm CPUs. They knew the temps were way off, so wouldn't a smart person try different programs to check the temps?