Recolor a motherboard?

ok, this is possible. however generally it is more time consuming, and troublesome then not. As a result not many people do it. Here are some tips

1) remove EVERYTHING from the motherboard, this includes heatsinks and anything else that can be removed (yes, heatsinks come off)
2) using tape, cover ALL ports, and connection points; including all exposed "pins" and CONTACT SURFACES (for heatsinks)
3) do not use primer or clear when painting. too many layers will create a thermal insulation effect which will cause parts to overheat; so only use one thin layer of paint
4) DO NOT use any oil or latex based paints. they will break down and damage the electrical parts.
5) only try this with a motherboard you can afford to destroy. Chances are good if you're not careful you'll get the paint somewhere which will cause damage to the board. this, plus the time required to do it, is why most people don't do this
6) you can paint the heatsinks but again, ONLY paint the non-contact surfaces, ONLY use a single THIN layer of paint
7) because you're probably using a water based paint you'll need to be 100% certain the paint dried, let it dry for a full day before reassembly.
 


In the vid, Linus didn't cover up the red PCI and RAM slots and spray painted it.
I want to do the same thing, but with green however doesn't the paint ruin the inside of the slots?
(I just want to recolor the red part of the ASRock mobo)
 


yes, it will ruin the slots if you don't cover them
 
i've seen it suggested to use cardboard stuck inside the slots or having an old pci/pci-e card inserted into the slot to cover that risk. of course the inside of the port would not be painted which may look odd with no card installed. needless to say painting the board would be a risk and i would not attempt it unless you are okay with possibly damaging the board.

even if you did get a very light coat of paint inside the slots, if you spent enough time you could likely scrape off just the contacts with a small tool to get them to work if the friction of pushing in and pulling out a card several times was not enough to wear the paint off the contacts. it would drive you crazy though. covering them would be the ideal solution if you did paint.

i would not say its a hard process (mask, paint, remove mask) however it would require much patience and very meticulous taping to get right.

honestly i do not consider it worth the risk to attempt, although that is clearly your choice to do so.