New laptop or old plugged laptop?

I've been using a hand-me-down laptop for almost 10 years. Battery is broken so it's always plugged in every use. I worry if the electricity usage is alarming at this point. It's an old HP Pavilion laptop and once in a while the fan is too loud. I still use it because of all the programs (CAD, PS etc) and files in it and also because it is still working.

Which is better, keeping this old plugged laptop or buy a new one?