I can make a hardware list.
Rule 1 of IT = coffee...... so get a cup of coffee to enjoy and keep the nerves calm.
*yeah its mostly joking on this one, but coffee is good to have
Note....
When working with computer hardware, motherboard, RAM, CPU, and cards like external GPU, Network, Raid etc card.
Be aware of ESD or electrostatic discharge..
Things nowadays isn't as sensitive as it was in the 90's.... when you could look at a RAM stick the wrong way and it broke.. But this is still something to keep in mind.. so either use an ESD armband and if you don't have that, Make sure to discharge yourself by touching ground.. That can be your sink or a metal water tap or similar... Then to make sure you dont build up new static electricity do not wear socks containing nylon while standing on a cotton carpet.
Then let your forearm lean against the computer chassis. That way you and the chassis is the same circuit and will have the same potential(i think that is the right english word)
End Note
But first.. do an inventory.. do you have it all. screws, cooling paste/Thermal Paste, cables, RAM, drives, CPU and motherboard is a bonus to have. You get what i mean.
New PSU? of not.. make sure the old is powerful enough for the new motherboard and graphic card etc.
Before you disassemble the old things.. Take a few pictures of how cables is attached and so on... This is in case you ever wonder.. Did i have that disk on Sata2 or Sata1.. or whatever it might be that you wondering about.
Make sure the motherboard screws is in the same place on the old and new motherboard.. If not. most chassis has removable screw spacers so you can correct it to fit the new motherboard.. and if its a new chassis, then the same, make sure they mach the motherboard screw holes.
easiest is to mount CPU, Ram and M.2 disk while you still have the motherboard on the table in front of you, then mount them when the motherboard is in the chassis.
Don't forget to mount the I/O plate in the back on the chassis before you put in the motherboard.
it is more common to forget then you think. *lol*
screws should be tighten firm but still light.. as you might want to remove them in the future without needing to drill them.
two finger grip on the screwdriver gives a nice feeling for it.
If its small air-cooler to the CPU i mount them while the motherboard is on the table.. if they are big and will shade some motherboard screw holes, then i mount the cooler afterwords.
attach cables and those things.
When you are finish... STOP.. walk away, take a minute break with a coffee or something.. Then go back and look.. is all cables attached, is everything in its right place.. is external PCI-e cards all the way down.. etc.
When you rechecked your own work, then its time to boot in to bios.. you have some tab on the computer health.. Keep an eye on the CPU temp just to check you got the paste right. In bios the CPU will run on max clock speed.. My goal is that the CPU not runs hotter then 45-50-55C
(i heard that intel gen12+13 runs hot compare to older gens so I'm not sure what bios idle temp they have)
That is my two cents to this thread.
Good luck on your computer build.