Hello I recently have an MK3S +, my impressions are perfect no failures but I find that over a period of more than 2 hours the extruder is very hot, I can not even put my finger on it, for the moment in order to remedy the problem I put a heatsink with a noctua powered by a rapberry pi in 5v. According to you can I connect this fan directly to the Rambo card, otherwise there is a solution to reduce the temperature. Thanks for your help.
This is normal. The extruder can be expected to hit 58c to 60c when printing in a 23c room.
An easy way to reduce the motor temp is to apply a 40x40x10 or taller heat sink using doublesided thermal tape.
Or adding a fan if you are printing inside an enclosure:
That does sound a little hotter than usual - you should expect the motor to get too hot to hold but not usually too hot to touch.
What filament are you printing? Some do take more work than others but if it's PLA or PETG it is worth checking the extruder assembly in case something is out of line, in partcular make sure you have not clogged the bondtech gears with filament dust or even scraps from a failed load/unload.