Heat is not by itself waste. It's what electricity turns into after it's done doing computer things. Efficiency is a separate question - how many computer things you got done per unit electricity turned into heat.
How many computer things you got done per unit electricity, and how many mechanical things you do with the temperature gradient between the computer and its heat sync.
For example, kinda wasteful to cook eggs with new electrons when you could use the computer heat to help you denature those proteins. Or just put the heat in human living spaces.
(Putting aside how practical that actually is... Which it isn't)
How many computer things you got done per unit electricity, and how many mechanical things you do with the temperature gradient between the computer and its heat sync.
For example, kinda wasteful to cook eggs with new electrons when you could use the computer heat to help you denature those proteins. Or just put the heat in human living spaces.
(Putting aside how practical that actually is... Which it isn't)