I am currently running an RPI 4b+ for a home server.

I was able to obtain a small PC with an i5 4690 in it. It has a 300W Be Quite! PSU and a Gigabyte GA-H97M MOBO. I would like to move my stuff from the RPI to this machine, as it has much more slots for HDDs.

For the sake of argument lets imagine I plug 4x4TB HDDs and 1 500mb SSD for the OS and run an Ubuntu LTS on it.

How much average electricity usage am I facing per month in kW/h? How much more would it be compared to the RPI which now has an external 1 TB HDD attached to it over USB?

Thanks a lot!