3770k IHS Removals - CPU temp dropped from 79C to 71C

[fgw]

Room Temp is 21c and i'm using a high flow watercooling system.

RT is reading low to mid 30's idle and mid 40's load.

But BIOS reads 18-20 idle.

as somebody already pointed out: its simply impossible to achieve temperatures below ambient!

bios temps are reported most times by reading the voltage from a thermal diode. its up to the bios software to convert this voltage into a proper temperature. thats the reason you see different temperatures with different bios versions. the algorithm used in converting the voltage into a temperature might be changed from bios version to bios version.

realtemp, coretemp, aida and similar software gets their temperature readings by reading intels digital thermal sensors (dts) which are located on the die within each core. this sensors directly report temperatures thus their readings don't need to be converted from voltage into temperature. but there is still a minor calculation to be performed on the temperature reading from this dts sensors. the sensors wont report absolute temperature but they report the distance to tjmax instead. in order to convert the dts value into an absolute temperature the reading needs to be substracted from tjmax.
unfortunately intel is not specifying this tjmax value for all processors. so its up to the software developer to "assume" a tjmax value to perform this calculations. as various software might use slightly different values for tjmax, the temp readings might differ slightly.

anyway, using a software which derives temperatures from intel dts sensors is the most accurate way to get cpu temperatures. its far more realistic than the readings from thermal diodes most bios displays.

to make all this even worse, dts sensors are not working very well at lower temperatures. intel designed this sensors to be accurate near tjmax. readings from this sensors might be off during idle but should be more accurate at higher (load) temps. this varies from processor to processor.

there is no way to get accurate temperatures from your processor. no matter what method or software is used, its almost ever wrong by some degree. there is only the question how far off the readings are ...

the point here is: your bios readings of 20c is definitely wrong if your ambient is somewhere near 20c! you can safely rely on the temps reported by realtemp which are about 10c above ambient during idle thus more likely to be close to reality.