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Day after day people keep comparing different temperature monitoring programs trying to find out which one to believe.
Often times people come up with, "My bios says xx temperature. Surely a big company like Asus or Gigabyte or whoever is reporting this temperature correctly." This temperature is read from an on board diode which has a great history of being completely incaccurate.
This is the same diode that SpeedFan uses to display CPU temperature.
Look at these numbers when the ambient temperature is 22C.
The bios reports the CPU temperature as 13C and after I boot up SpeedFan claims that it is now down to 12C. These numbers are meaningless so don't use them and certainly don't use them in any sort of comparison.
Even the core temperature is not being reported correctly when at a low idle temperature. A core temperature of 19C after installing my new Tuniq looks great but it's impossible for it to be 3C less than ambient temperature. An IR thermometer pointed at the copper heatsink is showing 27C which is likely much closer to the real idle core temperature.
The bottom line is that there is no way to determine a 100% accurate temperature for your cpu, 100% of the time. There are no sensors that are 100% accurate and no software that is 100% accurate to read these sensors.
The most accurate temperature sensors available are the digital thermal sensors ( DTS ) built into the Core 2 Duo. Intel created these to address some of the problems that people were having with the diode based sensors.
These can be read directly and accurately by using the CoreTemp 0.95 Option, "Show delta to Tjunction temp." The value returned is not an absolute temperature. It is an offset to the maximum temperature your cpu is designed to operate at or TjMax. When it reports 40C that is how many degrees you are away from when Thermal Monitoring will begin to start throttling your processor and eventually, hopefully, shutting it down if temperatures can't be controlled.
The DTS is accurate and repeatable from day to day. If you have 40C of headroom one day and you install a new fan and it shows you have 45C of headroom then you have lowered your core temperature by 5C. Given that the DTS is only an offset to an undocumented TjMax, it can't be used to make comparisons to temperatures with other C2D processors or other users.
Programs like CoreTemp or SpeedFan that examine your processor and assume a fixed TjMax value of 85C or 100C may or may not be right. TjMax is not documented by Intel so any software that uses an assumed TjMax to calculate an absolute temperature can't be assumed to be 100% accurate.
The last thing to keep in mind is that the DTS is calibrated and designed to switch on and off the Thermal Monitoring functions of your processor. For this function, it is accurate and very well documented. Unfortunately, it does not seem accurate when it is being misused to calculate an undocumented core temperature at idle. In my example above, it is obviously not accurate.
Hopefully this post clears up more confusion than it creates.
Often times people come up with, "My bios says xx temperature. Surely a big company like Asus or Gigabyte or whoever is reporting this temperature correctly." This temperature is read from an on board diode which has a great history of being completely incaccurate.
This is the same diode that SpeedFan uses to display CPU temperature.
Look at these numbers when the ambient temperature is 22C.
The bios reports the CPU temperature as 13C and after I boot up SpeedFan claims that it is now down to 12C. These numbers are meaningless so don't use them and certainly don't use them in any sort of comparison.
Even the core temperature is not being reported correctly when at a low idle temperature. A core temperature of 19C after installing my new Tuniq looks great but it's impossible for it to be 3C less than ambient temperature. An IR thermometer pointed at the copper heatsink is showing 27C which is likely much closer to the real idle core temperature.
The bottom line is that there is no way to determine a 100% accurate temperature for your cpu, 100% of the time. There are no sensors that are 100% accurate and no software that is 100% accurate to read these sensors.
The most accurate temperature sensors available are the digital thermal sensors ( DTS ) built into the Core 2 Duo. Intel created these to address some of the problems that people were having with the diode based sensors.
These can be read directly and accurately by using the CoreTemp 0.95 Option, "Show delta to Tjunction temp." The value returned is not an absolute temperature. It is an offset to the maximum temperature your cpu is designed to operate at or TjMax. When it reports 40C that is how many degrees you are away from when Thermal Monitoring will begin to start throttling your processor and eventually, hopefully, shutting it down if temperatures can't be controlled.
The DTS is accurate and repeatable from day to day. If you have 40C of headroom one day and you install a new fan and it shows you have 45C of headroom then you have lowered your core temperature by 5C. Given that the DTS is only an offset to an undocumented TjMax, it can't be used to make comparisons to temperatures with other C2D processors or other users.
Programs like CoreTemp or SpeedFan that examine your processor and assume a fixed TjMax value of 85C or 100C may or may not be right. TjMax is not documented by Intel so any software that uses an assumed TjMax to calculate an absolute temperature can't be assumed to be 100% accurate.
The last thing to keep in mind is that the DTS is calibrated and designed to switch on and off the Thermal Monitoring functions of your processor. For this function, it is accurate and very well documented. Unfortunately, it does not seem accurate when it is being misused to calculate an undocumented core temperature at idle. In my example above, it is obviously not accurate.
Hopefully this post clears up more confusion than it creates.
It worked fine the first few reboots, and then it would cause the computer to reboot as soon as I launch it. I thought maybe it was a BIOS tweak I did, so I changed the settings back, and it still rebooted the next time I tried to launch it. Kooky. I'd read at least one other person having the same issue. Oh well, at least I know my temps were showing in the 40s when I could get it to work.