do you connect the psu monitor plug to your mobos?

hi my hec 350w psu has a plug like the cpu fan(3 colors) , should i attach it to my mobo? its working fine w/ out me attaching it.. is that just to monitor fan speed and temp?? thnks mobo is p4s533

It's just to monitor fan speed, not temps. Your motherboard should have a 3 pin header just for the power supply if you'd like to take advantage of it.

I don't use the one for the PSU and use the spare headers for the case fans. Its personal preference, I suppose.

I would have liked four headers on the motherboard!