I'm posting this at Diego_Intel's request. I recently used the procedures from this post (DH87MC, Video fail beep code, no video until after OS load) to fix my board not posting, and after using the power button trick to get into the BIOS, my memory temperatures in the BIOS screen have been reporting 86°C instead of the usual ~44°C, even after a cold boot where the machine has been off for a while. This causes the MB to run the front, CPU, and back fans at full power. I tried reloading the BIOS defaults many times. I even re-flashed the BIOS with the same version. Nothing has fixed the problem. I've tried removing the memory sticks altogether and booting, then putting them back in. I've tried 1 stick at a time in every slot. Nothing has worked.
I should mention that the first time I tried powering on after 3 beeps, the machine seemed to hang. I tried a few more times, waiting sometimes for 4 or 5 beeps, but in those cases the machine would just power off. I noticed that sometimes it seems hung after the 3 beeps, but it just takes a while to start (~1min). I think that might have happened the first time and I powered it off, me thinking it was hung up. Maybe that screwed it up if it was in the middle of reconfiguring the BIOS.
While it's possible the memory chips' thermal sensors went bad simultaneously when they did, it seems highly unlikely considering they're in a cool environment and the case has 6 total fans, and I did not touch the memory DIMMs right before it happened. More likely it's a glitch in the BIOS.
I have gotten around the problem by telling the BIOS to ignore the memory temp when controlling the front, back, and CPU fans. I also maxed out the "normal" memory temperatures.
Coincidentally, the Intel Desktop Utility Summary screen reports the memory and VR temps at 170°C and 196°C, respectively. While the Board screen reports those same values, but as negative numbers. I don't understand why it is reporting different °C numbers than the BIOS when the other temps match what the BIOS is reporting.
I'm using 2 8GB Crucial DIMMs, model # BLS2KIT8G3D1609DS1S00.