I encountered a rather strange issue:
I have an Intel Coffee Lake, Core i9 9900KF 3.6GHz running on a MSI MPG Z390 GAMING PRO CARBON. Couple of hours ago I decided to check temperatures (for no reason, I just do that once in a while on game breaks) and msi command center was reporting 255 celsius cpu temp, 255 celsius mos temp, and I think the voltage was messed up also (not sure though, didn't make a print screen – unwise).
Since I was just finishing a gaming session I know there was no throttling, no reboots or any normal high temperature signs. Also at 255 degrees I'm pretty sure something would've melt (or at least smell like hell).
Since 255 is highest 8 bit number I assumed this may have been a sensor reading error.
I restarted and check bios and cpu temp was a casual 40 degrees. So I blamed command center but after restart all was fine there also.
So… any ideas what happened here? If it was a faulty sensor why didn't I encountered throttle (and shut down – temp is huge). If it was a software issue why did it go away without doing anything?
The scenario where a sensor reports a huge temp and pc doesn't shut down is what worries me most (even if the sensor is faulty, I prefer experiencing shutdowns / throttle than completely destroying my system or even worse, having a fire hazard right under my desk). How can I mitigate this?
Best Answer
At 255 °C, all the soldered connections would have melted (https://en.wikipedia.org/wiki/Solder_alloys), so, obviously, your assumption of readout (not sensor) error is valid. Most likely, the game was so optimized that it bypassed the code to check sensors (e.g. used interrupts or too much RAM).
Try using another tool to check CPU temperature, if that is a concern, e.g. HWiNFO, though "if it ain't broke, don't fix it". Rather than be concerned about the effect, prevent the causes of overheating, primarily dust -- in the heatsink, clogging ports, even stopping the fans. Other than that, the system monitors temperature and would speed the fan, throttle the CPU or shut down before damage occurs. Replacing thermal compound is not needed, in most cases.
Caveat: I've seen half the PC's in a server room shut down when the building HVAC failed, but with no permanent physical at all, just the impact on the business.