Mother Board Question

My Mother board is a 870a-G54 MSI Mob.

Now the question here is do i need to use the full 24 pins on my main connector or can i just use 20 pins be cause i have the option on both but not sure if it will start if i only use 20 pins.

 

Are you saying you have the option because of your power supply have a two part main connector? 20 pin and then a 4 pin? Or does it say on you MB that you have the two options?

 

It says on the new egg site Main connector 20+4 pin and then i have a extra 8 pins for the cpu.upgrading my cpu soon and need to know what kinda PSU i need to get be cause i am running a 550W but not sure if it will handle a newer 125w cpu i have a 65W cpu in there right now.

My mob specs are confusing.But here is the link--->>>http://www.newegg.com/Product/Product.aspx?Item=N82E16813130275

Just need to know if i need to use the full power main connector or am i able to just use 20 of them i have both options i guess.The PSU i looked at was going to cost like freaking 330.00 on newegg and that price has not dropped it has been the same price for over a year.

I really don't want to bye a 330$ PSU--->>http://www.newegg.com/Product/Product.aspx?Item=N82E16817194096

I have been using the full 24 pins since i plugged it in and have not tried the 20pin.