Do you think I might habe connected everything right and that I only need to install an OS and then it might work and light up? Because I was just worried about the cpu reaching such high temps and the pump not lighting up. Do you know if I can troubleshoot to see that everything is connected correctly?
You should get everything connected and working before installing OS. If you have everything connected go ahead and go into the bios and check your CPU temp. If CPU gets too hot it will shut down. 90c is not a problem for a few minutes
You need a 24 pin adaptor that jumpers together 2 pins. It allows the PSU to turn on and power everything except the motherboard. You can use a paper clip but you'll have to look up what pins to jumper together.