6 Pin PCIe Power

RyuKyu567 · Oct 12, 2018

I've been doing some research in a new pc build and one particular subject I am having some difficulty finding. To start off I have decided to go with the AMD X399 motherboard, now it has been a while since I have dealt with AMD but over the years they have made a pretty significant come back. With that said, information on the 6 pin PCI-e additional power is somewhat dated since I haven't had to deal with that since the 4 pin molex days. The purpose of this question is primarily to narrow down what brand of motherboard to purchase. For example, the ASRock has an easy location for the additional 6pin PCI-e power connector while the MSI has the dumb thing located in between the memory and top PCI-e slot (not exactly the easiest to route power cables for a clean look) so over all is the 6pin really required or not?

Now from what I understand each PCI-e slot can support up to 75w of power, however running multiple cards (mainly graphics) in a build may require additional power. So for example if your running 3-way SLI or 4-way SLI this makes complete sense. My question then falls to "what if your only running 2 cards in an SLI configuration?" I have looked up the manuals for all brands of AMD X399 motherboards and all they say for a 2 card SLI configuration is "If required, connect 6-pin additional power"..... kinda vague in my opinion. I am still in the process of looking up the power requirements on graphics cards but they all lead to the power on the 6+8 pin or 8+8 pin connectors. Not much is provided with the power requirements in the PCI-e slot.

In this particular build I will be using 2 GTX 980's but eventually will be upgrading to either dual 1080's or 1080ti's. So any information on this subject would be greatly appreciated.

RememberThe5th · Oct 12, 2018

Its depended, if gpu uses external power it will draw less from pcie, but here's a catch, some gpus draw more than 75W from pcie with external power, not sure where i saw the review but gamernexus i think has done that.

SkyNetRising · Oct 12, 2018

RyuKyu567 :

PCIE power connector is located on graphics card (not on motherboard).
On motherboard you can find either 4pin or 8pin CPU 12V EPS power connector (not compatible with PCIE 6pin or 8pin PCIE connector).

Edit. Ok, this is unusual. Apparently MSI X399 Gaming Pro Carbon AC and MSI X399 SLI Plus motherboards have PCIE 6pin connector onboard. It provides additional power to PCIe x16 slots.

I didn't find any Asrock motherboard with PCIE 6pin power connector onboard though.

Karadjgne · Oct 12, 2018

My MSI Mpower Z77 uses a 6pin supplementary pcie power connection on the mobo. It's main purpose was for cards that can draw closer to the pcie limits or above (multiple amd cards were measured in excess of 90w draws, early releases of Rx480 measured closer to 100w). It's an optional connection, depending on the gpu and the user if it's populated or not, normally unnecessary unless trying to OC already high pcie draw cards.

Gpus pull power from the psu directly (6,6+2,8pin pcie) and the x16 slot. It's rarely ever a balanced pull, on a 120w card for instance, you'd see maybe 40-50w pulled from x16 and the rest from the psu. But thats also dependent on the manufacturer, my Asus 970 has a Single 8pin, most had dual 6pin. This is important when considering the differences in ability. While standards dictate 75w for 6 and 150w for 8, that's standards, not reality. Each pin is capable of @5A, 60w max. A 6pin has 2x 12v leads so is capable of upto 120w, an 8pin has 3x 12v leads, so capable of 180w. This puts 2x6pin cards at a possible 240w draw, a single 8pin at a possible 180w draw. On a 225w card with dual 6pins, that's 75w from pcie and 150w from psu. OC that card, or it's a heavy spiker, and get draws of closer to 280w at times and the x16 slot can be an issue. The additional 75w mobo power can stabilize that power draw, giving the card any extra room it needs without unduly taxing the already high pcie draws through the 20+4 main mobo connection.

RyuKyu567 · Oct 12, 2018

- SkyNetRising

From what I have seen so far, it seems that the 6 pin is more common on standard ATX boards for the exception of the Gigabyte Aorus (which doesn't require it apparently). I haven't really looked at the extended ATX or the micro ATX since I'm not going to go with either of those types of boards, but for reference if you check out the ATX ASRock Fatal1ty X399 board you will see on the bottom right hand corner next to the SATA connections the 6 pin is located there. In my opinion that is fare more convenient compared to the middle of the board.

- Karadjgne

I agree that in the case of OCing a card that providing additional power would be required. In my particular case I'm not planning on overclocking at all. Haven't done that in years, since higher end CPU's and GPU's have so much HP its kinda unnecessary. But to be on the safe side I would like to find out as much as I can before any purchase so when the time comes to building the thing I don't potentially damage the board. I do see what your explaining though

Karadjgne · Oct 13, 2018

Most ppl buy a motherboard based on a few decisions. Color, brand, style, gimmicks. All you really do need is a mobo that has storage capacity availability (1ssd,1hdd, and 6 spare Sata ports?) etc. So most ppl will end up with only using less than half of what's available, the rest is just fluff extras. There's so much 'just in case' stuff on a mobo, that even for many users the 6pin pcie additional mobo connector is unused. Higher than lowest tier mobo's have all those extras in order to reach a wider possible user base and create sales in a highly competitive market. 6x Sata3 headers, I use 3. 6x usb2 headers I use 2. Hd/ac'97 audio headers I use HD. Anything eco? Joke! Easy OC button? Yeah, No!

There will be a lot of headers, ports, buttons, switches, possibilities that you will not use or ever have any use for, that 6pin pcie is probably one of them. However, you will have extra pcie on the psu, so if it's any sort of doubt, it's just another place to put a wire, won't hurt in the slightest having it.

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