So a 1000€ upgrade for the computer if an expensive PSU is needed.
That´s why I wanted to avoid GeForce cards, because all Radeon cards run without any problem on my 550w PSU (Corsair RM550x with modular sleeved custom cables).
While having the ASUS Radeon 5700 XT Super Advanced OC the semi-passive PSU fan that kicks in when 250w load is on the PSU never spun while gaming. So electricity-bill friendly is my computer.
And when using an Nvidia I am forced to use a 1000 watt PSU… Hm electricity is getting more and more expensive, I need to do some calculations about power consumption before upgrading 
With undervolting and limiting (power setting throttling, and limiting max FPS) a graphics card can run over 20°C cooler, most of the time it was 69° compared to 95°C and more.
That´s why undervolting and throttling is very important, especially when the thermometer will hit 40° this week I wonder what temperature it will have in my cozy attic apartment… 
All 6 Corsair magnetic levitation high speed fans are already set at 50% idle and 100% power when any hardware is hitting 70°C, and the RAM timings and voltage is now reduced because the RAM went very hot.
Undervolting prevents a computer from being destroyed during summertime…