Im doing a new build and im trying to salvage as much as i can. Im using a corsair tx650m psu and i have a prime a320m-k mobo. I figure my 24 pin goes into the according slot on my mobo and the 8pin marked cpu goes into the atx12v 4pin slot. Problem is my gpu has an 8 pin i need to connect and i dont have one coming from my psu. What type of cabling do i need?