Power Supply for Arduino based 3D printer

Hi guys,

So I'm currently trying to repurpose an old 3D printer with Arduino Mega 2560 and RAMPS 1.4 shield. The 3D printer consists of 5 stepper motors and a 40W single hotend. I'm planning to use a 12V 20A power supply (S 250-12). What precautions should I take and what can be changed?

You need to produce a lot more detailed description, link to the parts used, schematics....
3 lines of "word sallad" can't replace real documentation.

okay so its basically a Wanhao Duplicator i3 with the stepper motors, hotend and heating bed. Only parts im going to replace are the power supply and controller board, which is an arduino mega with a RAMPS 1.4 shield. The printer was originally rated to consume 240W.

Do You have any idea about what a controller board contains? I don't think so. The controller needs code, a program, that You will have to download.

yes i understand that much.

Good. What is the difficult, the blocking, question?