I think you may have an unrealistic idea of how much power low or mid-range gaming PC’s use. Only at the very top-end of PC’s with extreme overclocked components pushed to the limit would you come near 1000w (a $3000 Nvidia GTX 5090 graphics card can use 575w, as an example).

The Steam Machine uses effectively a laptop CPU (35W TDP) that’ll likely use 50 to 65w max, and the GPU is also a beefed up laptop GPU with a 110W TDP (it’ll probably peak at 140 to 150w, I’m guessing).

Overall it’ll probably idle at 10 or 15w, and likely use around 70w under average gaming, or 150 to 200w when pushed hard.

The Steamdeck is certainly still more power efficient, and if you find that it’s powerful enough for the games you play, there’s not much reason to consider getting anything else. But the Steamdeck will be pretty power efficient for a desktop. It kinda has to be, since it only has a single fan for cooling.