# Water-cooled CPU and air-cooled GPU

TODO

## PID Usage and Example

TODO

The default configuration works well on a PC with a water-cooled CPU and an air-cooled GPU:

* Uses a supply water temperature sensor and a case temperature sensor
* Controls supply water temperature to 2-3°C above case temperature (initial setpoint is 28°C)
* Fan output percent is generally between 45%-60%, unless CPU is loaded
* If case temperature is within 2°C of supply water temperature, and fan output percent is greater than 60% for 20 seconds, the setpoint increases by 0.25°C

For example, the fans are controlled to keep supply water temperature at setpoint:

![Example 1.1](https://4099583760-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M1RzmweizdbxT9i_NQb%2F-M1TZ80arhsTGjIL0i0r%2F-M1TZ9kf0vIS_TSoBmwg%2Fex1.1.jpg?generation=1583208255828588\&alt=media)

In the same dataset as *Example 1.1*, and only plotting fan RPMs and DeltaT (return temp - supply temp), observe the fan speeds trailing DeltaT (which represents CPU load in the following example):

![Example 1.2](https://4099583760-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M1RzmweizdbxT9i_NQb%2F-M1TZ80arhsTGjIL0i0r%2F-M1TZ9khyVPy30MSYmNk%2Fex1.2.jpg?generation=1583208251701344\&alt=media)

Next, an air-cooled GPU is used for about 30 minutes, showing *setpoint adjustment* keeping fan speeds within the configured range:

![Example 2](https://4099583760-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M1RzmweizdbxT9i_NQb%2F-M1TZ80arhsTGjIL0i0r%2F-M1TZ9kjBS5bHrtyUp5S%2Fex2.jpg?generation=1583208250295424\&alt=media)

The same behavior is observed, except caused by room temperature changes, in this example:

![Example 3](https://4099583760-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M1RzmweizdbxT9i_NQb%2F-M1TZ80arhsTGjIL0i0r%2F-M1TZ9kl6KxOw88aEMSI%2Fex3.jpg?generation=1583208253005799\&alt=media)

When only the CPU is loaded, the setpoint temperature does not change, and the fans speed up as needed:

![Example 4](https://4099583760-files.gitbook.io/~/files/v0/b/gitbook-legacy-files/o/assets%2F-M1RzmweizdbxT9i_NQb%2F-M1TZ80arhsTGjIL0i0r%2F-M1TZ9knKMK_NuIEoRL6%2Fex4.jpg?generation=1583208254767478\&alt=media)