RealTemp & Speedfan II (Huge difference between them)

You need to make sure you get Speedfan 4.40. The developer fixed his problems, and now his core temps are right in line with Real Temp.

Before that it was not something you could rely on.

If Intel's specification of Tjmax 100C for the T5250 is correct then Real Temp would be right. You appear to be using the Gulftown version of RT but it's probably only aesthetic.

Tjmax is the temperature the cpu will start throttling, if enabled. It will probably shutdown some ~20C above that. Since this mechanism is only supposed to be a secondary safety feature for the cpu your ACPI should take care of things before then.

http://processorfinder.intel.com/details.aspx?sSpec=SLA9S

Here's the basic formula that all software uses:

Reported Temperature = TJMax - Digital Sensor Reading

All software is reading data from the exact same digital sensors. This sensor counts backwards so as your CPU gets hotter, it counts down instead of up. The digital sensor data is reported as Distance to TJMax in RealTemp. To convert that data into a meaningful temperature you need to know what core temperature your CPU will be at when it counts down to zero. This is called TJMax or the Intel site lists that as the Thermal Specification.

Luckily for your CPU, Intel says this number is 100C. If SpeedFan or other software assumes that this is 85C then hopefully by looking at that formula you will see that other software will report your core temperatures 15C cooler than what RealTemp is reporting.

Laptop CPUs can run very hot because many of them are poorly cooled. A heatsink that is not attached snugly with a poor application of thermal compound will result in high core temperatures. If you ever get bored you can pull your laptop apart and try to re-engineer your heatsink. Your core temperatures are presently fine. These CPUs won't explode even when operated in the 95C to 100C range for extended periods of time. Your lap will complain before your CPU does.

Stop worrying and enjoy your laptop.

RealTemp 3.50 beta
http://www.sendspace.com/file/u79b5p

Nikolayevich2010 said:

BTW Is there a way to modify the TJMax in speedfan ?

Click to expand...

You can specify an offset for every core.

Nikolayevich2010: You're not understanding this correctly. SpeedFan and RealTemp are both using the same formula and both reporting the temperature of your CPU. The difference is that SpeedFan is using the incorrect TJMax in its calculation. If it uses a TJMax of 85C when the actual TJMax is 100C then SpeedFan will always report exactly 15C less than RealTemp.

When the internal sensor is reading 40

RealTemp = 100 - 40 = 60C
SpeedFan = 85 - 40 = 45C

When the internal sensor is reading 25
RealTemp = 100 - 25 = 75C
SpeedFan = 85 - 25 = 60C

Now does it make sense?

The internal sensor that Intel uses is the equivalent of a reverse thermometer. As the core temperature gets hotter, this sensor counts down to zero. It's up to software to use the correct TJMax for that processor to convert the sensor data into a meaningful temperature number.

If you want SpeedFan to report the same temperature as RealTemp, you will have to go in and set an offset of 15 as burebista has shown. This will correct for the fact that SpeedFan didn't bother to follow the Intel documentation for your CPU.

Here's my E8400 running for 3 hours with the fan disconnected. It got a little hot and bounced off the Intel thermal throttle for 3 hours but never skipped a beat. Now that's what I call Prime stable.



This is my daily use CPU and I'm still using it today. I've been running it at 4 GHz and 1.40 volts for a long, long time without any problems.

When you are not stress testing your computer, the temperatures will be very reasonable and you shouldn't have any long term problems.