How to Lower CPU Speed

A central processing unit or CPU acts as the brain of a computer that carries out the calculations necessary for the computer to run. The faster the CPU runs, the more heat it creates and the more power it consumes, which can result in crashing and system damage if the heat buildup is too great. It is possible to set a CPU to run at a slower speed, also known as "underclocking," though underclocking should only be done with caution, as it can potentially cause system instability.

Instructions

1. Turn off your computer.

2. Start up the computer, and press the appropriate key to enter BIOS setup. As your computer powers on, there should be a screen that appears briefly that says "press key x" to enter setup, or something to that effect. The key you must press will vary depending on your BIOS, but it is usually the Delete key or one of the F keys (e.g., F1, F2).

3. Use the BIOS navigation instructions that appear, and search for a menu dealing with CPU and bus speed. Every BIOS is somewhat different, so the exact titles and options available will vary.

4. Lower the front side bus (FSB) speed. This speed determines how fast the CPU will process data. You can also lower the FSB multiplier value to lower the speed. After altering a value, save the changes. Try lowering the speed by 10 to 20 percent, as lowering it further might make your computer run too slow.

5. Lower CPU voltage. If you lower your FSB speed or multiplier, your CPU will run slower, resulting in less need for power to the CPU. As a result, you may want to change the CPU voltage before exiting the BIOS. Many BIOS menus have a field for changing CPU voltage. Lower the voltage by a percentage similar to the change in CPU speed that results from altering the FSB speed and/or multiplier. The BIOS should display a new clock speed for your CPU based on the changes to the FSB speed and multiplier on the screen where you made the changes.

Tips & Warnings

• Altering BIOS settings can cause system instability.

• While underclocking can lower a CPU's speed, it is usually best to increase CPU cooling to limit CPU heat, since it does not risk instability and a loss of performance.

• Take note of the original values for any options you change (FSB speed, multiplier and CPU voltage) so that you can change them back if you experience any problems.

References

• CPU Undervolting & Underclocking: A Primer