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Forum Home > General Hardware > How to know if your PC is overheating

Malco1987
Site Owner
Posts: 18

Here are the maximum temperatures for the most popular CPUs.


Keep in mind that the onboard measurement facilities are often inaccurate and may report temperatures that are too low. This is especially the case with motherboards that use a thermal sensor below the CPU to "guess" the CPU temperature. The temperature values displayed by the BIOS have usually a correction value added, to compensate for this problem -but in some cases this correction value may be too low, or the sensor might not be in good contact with the CPU.

This means: If the maximum allowed temperature for your CPU is 95°C, and your motherboard reports a CPU temperature of 90°C, then you are not on the safe side.


However, this doesn't mean that you should start to panic when your Athlon XP CPU reaches 60 degrees celsius, for example. Most people tend to underestimate normal CPU operating temperatures - maybe due to overclockers bragging with their super-low CPU temperatures in forums.


Also, note that these values are for CPUs that are not overclocked. Overclocked CPUs may run unstable even if their temperature is way below the maximal specified temperature.

What happens if the maximum operating temperatures are exceeded? If your cooler is insufficient and the temperature exceeds the maximum operating temperature, then this does not mean that the CPU is automatically damaged. With AMD CPUs, you will usually encounter crashes if the CPU is overheated; but these go away as soon as the CPU is cool again.


In the long term, running the CPU at a temperature that is too high may reduce the CPU life, since an overheated CPU is more prone to electromigration - even if it runs stable.

With P4 CPUs, the CPU will turn its speed down automatically when it overheats. No damage to theCPU is possible, but the system will get slower while it's hot (which, in some cases, users might not even notice).

If you attempt to operate a CPU without heatsink at all, recent AMD CPUs will usually be permanently damaged within seconds, unless special protection circuitry is available on the motherboard. P4 CPU's will run excessively slow without cooler.


The purpose of this page is to give you a quick overview of typical maximum operating temperatures for common CPUs. In the case of Intel CPUs, values vary a bit; if you need precise information for one specific CPU model, please use the datasheets on the CPU manufacturer'swebsite, or visit ChrisHare's Processor Electrical Specifications page - there, you will find more details, and also data for more exotic CPU types than the ones covered here.

Higher is better here On cooling-related websites, lower temperatures typically correspond to better products.On this particular page, the opposite is true: The higher temperatures aCPU can withstand, the less cooling is required. CPUs with low electrical power, but high temperature rating can be used with more quiet and more compact coolers. An example for such a CPU is thePentium-M, which dissipates less than 25watts, but may reach temperatures of up to 100°C. The worst-case example is the Pentium 4 Extreme Edition 3.46GHz, which dissipates over 110 watts, but may only reach a maximum temperature of 66°C. Obviously, you need a large and possibly loud cooler here.

 

 

NOW FOR THE DATA







The temperatures specified for AMD CPU's max case surface temperatures. These CPU's do not have an internal diode to measure CPU temperature. The accuracy of the CPU temperature measurement depends on the motherboard; therefore, it is possible that the CPU overheats even though the CPU temperature reported by the motherboard is below the specified maximal temperature.



Pentium III max temperatures are the maximum temperatures reported by the thermal junction inside the CPU.



Celeron max temperatures are the maximum temperatures reported by the thermal junction inside the CPU, unless otherwise specified.



Pentium II temperatures are the maximum temperatures of the thermal transfer plate (on which the heatsink is installed).




Note: Pentium 4 and Pentium D temperature specifications indicate the maximum cover temperature, which is typically lower than the temperature reported by the internal thermal diode. Therefore, your system may be running fine even if the reported "CPU temperature" in the BIOS is higher than the temperature specified here. This does not mean that you're on the safe side, though.



Pentium Pro temperatures are maximum surface temperatures.



Typical maximum power usage of common CPUs and overclocked CPUs


Apart from the maximum CPU operating temperature, the maximum power usage under typical worst-case conditions (thermal design power) is also essential for selecting a suitable cooling system. To findout about CPU power usage, please check out Chris Hare's Processor Electrical Specifications page. There, you will find values for unoverclocked CPUs running at their specified voltage.


How can you estimate power usage of an overclocked CPU based on this value?


The theory behind calculating the power usage for an overclocked CPU is very simple: Power usage is proportional to clockspeed, and proportional to the square of the core voltage.


Before we express this as a formula, let's introduce the following variables:

 


 

  • Ps is the power usage of the non-overclockedCPU
  • Po is the power usage of the overclocked CPU
  • Fs is the clock speed of the non-overclockedCPU
  • Fo is the clock speed of the overclocked CPU
  • Us is the default voltage of the non-overclockedCPU
  • Uo is the voltage at which the overclockedCPU runs


Here is the formula:


                                      Po = Ps * (Fo/Fs) * (Uo2/Us2)


A simple example:


We want to calculate the maximum power usage of a Athlon "Thunderbird" 1.33 GHz CPU  overclocked to 1.6GHz using 1.9V voltage. From this page, we find out that:


  • Ps is 70W (max)
  • Us is 1.75V

Also, we know that


  • Fs is 1.33GHz
  • Fo is 1.6GHz
  • and Uo is 1.9V


Therefore:


              Po = 70 W * (1.6/1.33) * (1.92/1.752)= 99.26 W


Values calculated using this method are not very accurate, since I/O voltage and FSB speed is not taken into account. However, they should be precise enough to help you decide what kind of power supply and cooling you need.


Disclaimer


The information here is provided by The Heatsink Guide & Malcomp Tech Arena WITHOUT WARRANTY of any kind. If you are designing a system and need to have accurate information on the maximum temperature of a specific CPU, please rely on the information provided by the CPU manufacturer, and not the information here. Future CPU models (even if they are marketed under the same name/with the same MHz) as the CPUs mentioned here may have different thermal specifications.

 


 

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Contacts: Lime: 342-9787 | Claro: 597-2988

E-Mail: [email protected]


August 8, 2009 at 3:20 AM Flag Quote & Reply

yaaDKLoze
Member
Posts: 3

so when u ago teach a class so me can sign up?

August 26, 2009 at 9:42 PM Flag Quote & Reply

Malco1987
Site Owner
Posts: 18

yaaDKLoze at 09:42PM on Aug 26, 2009

so when u ago teach a class so me can sign up?

lol :D... you'll be the first to know bro

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Contacts: Lime: 342-9787 | Claro: 597-2988

E-Mail: [email protected]


August 29, 2009 at 10:56 PM Flag Quote & Reply

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