MSI 990FX-GD65 V2 / 8 pin CPU and 6 pin PCIE but why?

mykalcook

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Aug 6, 2013
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I just built a rig (2 of them actually) that use this motherboard.

I have noticed that there is an 8 pin power connector for the CPU, and a 6 pin connector for the PCIE bus (i believe that's what it's for)

Why is there a 6 pin power connector for that on this board? I have a 750 watt power supply, and am using 2 GTX 570 SC in SLI. All of my 6 pin connectors were being used by the cards and so I used a 2x molex to 6 pin pcie connector that I had laying around. However, I am aware that the end with the 6 pin connector is only using 5 of it's contacts. Still, the computer boots up so I'm left wondering a whole lot of things.

I actually could use some education on PCIE and their power connectors, because I don't know what pins are carrying the juice, which ones are grounded, what is absolutely necessary, what molex/sata/pcie connectors will work together, which ones wont, what amps to look for, separating the rails from each video card, etc

So yeah, if no one is willing to teach me about PCIE that's fine, at least tell me why this board has an 8 pin connector for the CPU and a 6 pin for the PCIE channel. I had an SLI setup on an AM2+ board and that didn't have one. So I await an answer...
 

mykalcook

Honorable
Aug 6, 2013
17
0
10,520


Is it necessary to have it plugged in?