All PSUs have efficiency curves and are rated differently. You can’t always trust the published numbers either.
Your 750W PSU might pull closer to 937W from the wall when you’re asking it for a full load, if it’s rated at 80% efficiency. Those ratings are not linear though and usually have a sweet spot around 80% of max load.
I.e. It will be most efficient at around 600W (80% of the 750W max load). At higher loads it will be even worse, possibly drawing closer to 1000W from the wall.
Also efficiency.
All PSUs have efficiency curves and are rated differently. You can’t always trust the published numbers either.
Your 750W PSU might pull closer to 937W from the wall when you’re asking it for a full load, if it’s rated at 80% efficiency. Those ratings are not linear though and usually have a sweet spot around 80% of max load.
I.e. It will be most efficient at around 600W (80% of the 750W max load). At higher loads it will be even worse, possibly drawing closer to 1000W from the wall.