Dynamically modified fan speed table for cooling a computer

1. A method, comprising:

measuring a temperature within a computer system;

dynamically selecting a fan speed step in response to the temperature received, wherein the fan speed step is selected from a fan speed table defining a finite number of fan speed steps each having an associated fan speed;

operating a fan at the dynamically selected fan speed step, wherein the fan is positioned to drive air through the computer system where the temperature is being measured;

measuring a fan output variation over a prescribed time interval;

automatically modifying the fan speed table to change the fan speeds associated with each fan speed step, wherein the fan speeds are changed as a function of the measured fan output variation while continuing to drive the fan, and wherein automatically modifying the fan speed table includes obtaining an upper and lower fan output value from the measured fan output variation and changing a minimum fan speed step, a maximum fan speed step, and an interval between fan speed steps as a function of the measured fan output variation.

2. The method of claim 1 , wherein measuring the fan output variation comprises obtaining a variation in fan speed, a variation in the dynamically selected fan speed step, a variation in a fan voltage, or a variation in a fan power.

3. The method of claim 1 , wherein the fan output variation is measured at preset points within the prescribed time interval, and wherein the fan speed table is automatically modified in response to expiration of the prescribed time interval.

4. The method of claim 1 , further comprising:

modifying the fan speed table to restore the fan speed steps to default values in response to a detected thermal event.

5. A method, comprising:

measuring a temperature within a computer system;

dynamically selecting a fan speed step in response to the temperature received, wherein the fan speed step is selected from a fan speed table defining a finite number of fan speed steps each having an associated fan speed;

operating a fan at the dynamically selected fan speed step, wherein the fan is positioned to drive air through the computer system where the temperature is being measured;

measuring a fan output variation over a prescribed time interval; and

automatically modifying the fan speed table to change the fan speeds associated with each fan speed step, wherein the fan speeds are changed as a function of the measured fan output variation while continuing to drive the fan; and wherein automatically modifying the fan speed table includes refining a fan speed granularity by narrowing a range of fan speeds associated with the finite number of finite fan speed steps without changing the number of fan speed steps.

6. The method of claim 5 , wherein measuring the fan output variation comprises obtaining a variation in fan speed, a variation in the dynamically selected fan speed step, a variation in a fan voltage, or a variation in a fan power.

7. The method of claim 5 , wherein the fan output variation is measured at preset points within the prescribed time interval, and wherein the fan speed table is automatically modified in response to expiration of the prescribed time interval.

8. The method of claim 5 , further comprising:

modifying the fan speed table to restore the fan speed steps to default values in response to a detected thermal event.

9. A method, comprising:

measuring a temperature within a computer system;

dynamically selecting a fan speed step in response to the temperature received, wherein the fan speed step is selected from a fan speed table defining a finite number of fan speed steps each having an associated fan speed;

operating a fan at the dynamically selected fan speed step, wherein the fan is positioned to drive air through the computer system where the temperature is being measured;

measuring a fan output variation over a prescribed time interval including obtaining an average and a standard deviation of the fan output over the prescribed time interval; and

automatically modifying the fan speed table to change the fan speeds associated with each fan speed step, wherein the fan speeds are changed as a function of the measured fan output variation while continuing to drive the fan.

10. The method of claim 9 , further comprising:

in response to the standard deviation being less than a standard deviation threshold, modifying the fan speed table to narrow the range of fan speed steps about the average of the fan output.

11. The method of claim 10 , further comprising:

in response to the standard deviation being equal to or greater than the standard deviation threshold, modifying the fan speed table to restore the fan speed steps to default values.

12. The method of claim 9 , wherein measuring the fan output variation comprises obtaining a variation in fan speed, a variation in the dynamically selected fan speed step, a variation in a fan voltage, or a variation in a fan power.

13. The method of claim 9 , wherein the fan output variation is measured at preset points within the prescribed time interval, and wherein the fan speed table is automatically modified in response to expiration of the prescribed time interval.

14. The method of claim 9 , further comprising:

modifying the fan speed table to restore the fan speed steps to default values in response to a detected thermal event.