Adjustable computer cooling system

I offer an easy-to-manufacture and easy-to-use computer fan control system.
The system has 3 positions:
- disabled;
- low noise mode;
- maximum mode.
First, install additional fenestrons under the hard drive.
To reduce noise, fix fenestrons on an elastic suspension.

I applied rubber rings and wire extensions (all in a hurry)

To control the cooling, I had to spoil the front plug:

We insert a switch and an LED into the holes made to indicate the operating mode.

Now about the filling.

The scheme is presented in the figures and photos.
The circuit is not critical to the choice of radio elements:
- 1 kOhm resistors of any power (mlt 0.125 W used);
- R load - a powerful resistor of at least 3 W (used PEV-4)
- Any diodes with a current of at least 0.5 A (used 1N4007)
- relay 2x positional U pit = 12 V (used REC 23 (12V, 1A))
- two-color LED.

That's all.
The only thing that needs to be tuned is the multi-noise voltage.
In our case, the system controls three fenestrons, the Input (120 mm) and two blower drives (60 mm). It was experimentally established that at a voltage of 7 volts the noise is not large and the performance is acceptable. A voltage of 7 volts was set with a wire rheostat during the operation of fenestrons - a resistance of 20 ohms was obtained.
In your case, the load resistance R may have to be selected.

Here's what happened:

Switch Position:
0 - fenestrons are off (indicator color is red);
I - low-noise mode (indicator color yellow)
II - maximum mode (indicator color is green)
The author of the craft: Ika_tander