The motherboard has a 2x4 ATX 12v connector AND a 2x12 ATX connector.
The PSU has a 20+4 wire which I understand is to go to the 2x12.
My question is what does the 2x4 connector do? Is it to power the CPU? The PSU has two 2x2 wires, named "CPU1" and "CPU2", so I should connect both of these to the 2x4 then?
Great, thanks. I felt it is better to ask than connecting the wrong wires to the mobo.
That's completely understandable. It's better safe than sorry, right?
Good luck with the build.
The READ before posting about boot problems! sticky at the top of the forum has quite a few more troubleshooting ideas. It's a good idea for any new builder to read through the checklist so they can avoid some of the most common mistakes.