Where you use HCF4046?

The HCF4046 integrated circuit is a phased locked loop control IC, typically this would be used in a switched mode power supply, however these are only ever needed where the load is frequency dependent and also drifts. In PC PSUs, a PWM IC is used instead to regulate power very precisely, such as a TL494.

In short, the 4046 would not be used in any computer equipment!