What is the rough watt consumption of a high end GPU and CPU?
Depends on the exact CPU and GPU. 6950XTs are 330W at stock, 400+ when you unlock the power limits. 3090 Tis are 450W. For CPUs, if you're using a 12900K(S) they run at 300-400W depending on the exact load. For a 5950X they'll hit 200W before they become uncoolable.
That said, with the way silicon works, the colder it is the more efficient it gets, so the power consumption numbers at ambient really don't matter when it gets cold and overclocked. Sometimes it gets way more efficient (12900K, for example, runs at 200W when fully overclocked when cold) and sometimes they get really power hungry (3090s, for example, if power limits are unlocked and you get full voltage control they'll draw 1000W+ given enough cooling).
That said, GPUs only make sense to overclock when you manage to get full voltage control. With locked voltages you're not gonna realistically get any more performance by going cold, an extra 100-200MHz at most (not noticeable in game, important for benchmarking though). Because you need full voltage control in order for this to make sense, you have 2 options: 1.) buy a Kingpin edition GPU or 2.) hardmod the card.