

PSU can indeed make a pretty big difference.
If you only have a 80 Plus certified PSU, and see 65 watts drawn at the wall, your system might actually only be using 52 watts, the remaining 13 watts are wasted as heat in your PSU. 80 Plus Gold, Platinum, or Titanium all carry higher efficiencies, but also cost more to buy.
Actual efficiency is also heavily influenced by the load. Most PSUs are most efficient at 50% load. Both lower and higher loads with result in worse efficiency.
Here’s an article with some more details: https://www.technewstoday.com/power-supply-efficiency/
https://piefed.zip/post/1240538