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Step By Step: How to Stress Test an AMD Quad Core (X4) CPU

written by: R.L. Flowers•edited by: M.S. Smith•updated: 5/20/2011

Have you been overclocking your AMD X4 CPU? Perhaps you just want to make sure that your computer has enough cooling capacity to stay cool under high gaming loads. This article will show you how to properly stress test your AMD quad core CPU and monitor the results.

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    Introduction to the AMD X4 quad core CPU

    AMD Phenom II X4 AMD's Phenom II and Athlon II X4 processors have become very popular quad core CPUs. They compare very favorably to Intel processors not only in terms of speed but especially in price. AMD's quad core CPUs are available for under $100, but Intel's quad core chips start at $150. Clearly, AMD has a price advantage. One thing that many people love is that for the enthusiast, the Black Edition Phenom II's can be overclocked quite a bit, and some can even be 'unlocked' from dual core to quad core. When this is done, however, it is vital to keep the processor cool.

    For these reasons, this article will show how to stress test your CPU to the maximum.

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    Preparation for Stress Testing: Monitoring

    Stress testing is made to intentionally test the CPU at its maximum processing capacity. If we were stress testing your car, we'd be getting on the longest, straghtest road and going as fast as we could, pedal to the metal. Surely that would make the car run hot. Would it run too hot? In a car, we'd look at the temperature gauge. Your computer also has a thermometor in it, so lets look at how we can monitor the CPU so that we can tell if it is overheating.

    Clean your computer

    If we're going to test your CPU to the maximum, it is vital that your computer is clean. Open it up and look at the CPU heat sink and fan. Do they have any dust on them? Take your computer outside and give it a good airing out. You can use a can of air such as are available at most office supply stores. You can also use an air compressor. Use the air nozzle attachment at a distance of about 24" (.6m) to avoid damage from the high pressures that a shop compressor produces.

    Now that it is cleaned out, lets move on.


    speedfan-idle SpeedFan (available at is a utility that makes it easy to monitor both fan speeds and CPU temperatures alike. Download and install SpeedFan. Open the program and click on "Configure" and go to the "Options" tab. Now select "Fahrenheit" as the temperature format.

    Go back to SpeedFan. Look at the temperatures, and maybe eve write down what they currently are for reference later. We are concerned with "Temp1" which is the main CPU temperature. Leave SpeedFan open. We're going to use it to watch our temperatures.

    When stress testing your computer, it is best to make sure the temperature stays below 70° Celsius.


    Go to and download the proper version of Prime95 for your PC. Don't worry about signing up an account. For our purposes we can skip that part. Follow the rest of the directions on the Prime95 page. This program will put your computer through its paces like no other. Open the program and click "Just Stress Testing."

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    Pedal to the Metal!

    Pedal to the Metal! We're now ready to start it up. This part is most critical but it is also the easiest. In Prime95, select the second test "In-place larte FFTs." Make sure that the number of torture test threads is the same as the number of cores in your processor, which in this case is 4. Make sure all other programs are closed and go ahead and click on "OK" to begin the test. Many overclockers run the stress test for at least an hour before they proclaim that their system is stable. You will need to run it for at least 10 minutes to get the most accurate results.

    Watch the Temperatures!

    Keep an eye on SpeedFan. If the temperature gets past 70° Celsius, click "Test" and then "Stop" on Prime95. Your system needs some work before it will be able to withstand the stress test. That part will be covered in another article.

    How did you do?

    Did the temperature stay within reasonable ranges? Hopefully so. If you got a "Blue Screen of Death" in Windows, then more tweaking is needed. That is also out of the scope of this article and will be covered separately. How high did the temperature get before it stabilized and did not heat up any further? My own took about 7 minutes before it topped out at 60°. Yours may vary. Mine is overclocked from the stock 3.1Ghz to 3.4Ghz, which makes it run hotter.

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    In Conclusion

    So, is your system up to providing the maximum your CPU can provide? Hopefully when you stopped the test the temperature dropped down to its pre-test levels within a very short time. If it does not, then your cooling is probably not adequate. The CPU coolers that come with AMD processors are of poor design and are hardly adequate, and you may need to get an aftermarket one. That too will be covered in another article.