I have a Z390 motherboard. 
 
There is a 6-pin power connector on the motherboard. See the attached pic.
 
The manual says that this is to be connected to +12V on all 3 +ve pins and GND to all 3 -ve pins.
 
I have an EVGA power supply. 
 
There are plugs for MOBO, CPU (1,2), VGA (1,2,3,4), PERIF, SATA.
 
Which plug / cable should I use to connect the 6-pin connector? The CPU (1,2) result in 8-pin connectors. The PERIF results in things that are totally differently shaped. The SATA only comes out with SATA connectors. The VGA ones can split into 6+2 which seems like that might work... but they say VGA.
 
So I am guessing just based on physical I should use the VGA one... but since I have two graphics cards I have used all four VGA connectors.

Cool GTX
7. Supplemental PCIe 6-pin Power ConnectorThere is a 6-pin PCIe connector at the bottom of the motherboard (See Page 36for more specifics to the connector itself, and associated wiring/pinouts). This connector provides dedicated power to the PCIe x16 slots, augmenting the power provided by the 24-pin and the GPU directly. This is optional for a single card solution, but is recommended for SLI, CFX, and dual-processor video cards
 

+1

simonlok
 
 
Use the "VGA" cable 
 

You did not mention which GPU & PSU you have ?

 
 
I have an EVGA Supernova power supply. It has 4 VGA power outputs. There is no fifth VGA power output for this motherboard connector.
 
 
This is dumb.
 
 
 

 
(Page 14 excerpt)
 
7. Supplemental PCIe 6-pin Power ConnectorThere is a 6-pin PCIe connector at the bottom of the motherboard (See Page 36for more specifics to the connector itself, and associated wiring/pinouts). This connector provides dedicated power to the PCIe x16 slots, augmenting the power provided by the 24-pin and the GPU directly. This is optional for a single card solution, but is recommended for SLI, CFX, and dual-processor video cards
 
(Page 36 excerpt)
 
 EVGA strongly recommends plugging in this connector for 3-way, 4-way, and Quad SLI, regardless of GPU.
Although the Z390 FTW does not support 3-way or 4-way SLI, connecting a 6-pin PCIe connector is recommended if running two or more high-end graphics cards in SLI, or running multiple cards in a high-performance environment
 
 

 
I read that in the manual before you posted it. Nowhere in there does it say anything about using the VGA connector. 
 
 

It says it right there in bold. The VGA cable is a PCIe cable. They are one and the same.

Supernova is a very very broad term as EVGA has 450w-1600w supernova power supplies in many different ratings along the way.

Which power supply do you have specifically.

Also, this is supplemental power, not required. You shouldn’t have a need or requirement to install the 6pin vga/pcie connector.

 

the_Scarlet_one
It says it right there in bold. The VGA cable is a PCIe cable. They are one and the same.

 
I guess one is suppose to infer that VGA = PCIe even though those two acronyms share zero characters in common and nowhere in those two paragraphs does the word VGA show up. 
 
Obviously VGA is one of the many kinds of PCIe cards you can plug in, but PCIe is clearly a superset in the class of objects that would be known as VGA. Poor documentation is my opinion of what this is. 
 

the_Scarlet_one
is a very very broad term as EVGA has 450w-1600w supernova power supplies in many different ratings along the way.
 
Which power supply do you have specifically.
 

 
I went onto the EVGA web site.
 
It has a tool that selects which power supply you should use.
 

 
I put in exactly what I was going to do, and it told me what I should get, and I did what it said to do.
 
See attached.
 
Another example of what I would consider to be poor documentation on the part of EVGA. Either you are suppose to plug it in or you are not suppose to plug it in. If you are suppose to plug it in then the calculator on the website should tell you to use a power supply that has the right plugs on it. 

the_Scarlet_one
Also, this is supplemental power, not required. You shouldn’t have a need or requirement to install the 6pin vga/pcie connector.

I figured as much. I did have a situation a few times where failing to plug in the 8 pin ATX connector on the motherboard would result in either the system not starting up or in the very old days of the AMD Athlon stuff the CPU actually smoked. 
 

Simonlok,

Since the motherboard does not require the 6 pin supplemental power, there is no reason to put it into the power meter. It should not suggest you a power supply you do not need, and in this case, you do not need the extra 6 pin, so it isn’t suggesting it.

Google is your best friend here.. google pcie cables versus vga cables. The answer is readily available all over google, answer thousands of different ways to say the same thing.

You can also look at the specs of the power supply since they do not list any vga cables and only list pci cables on the power supply spec section of the page. Once you get into the documentation, it goes into greater detail that fits into exactly what you have asked, with examples below.

Here is the power supply documentation for the one you are looking at you can see that the 850-T2 shows VGA 1, 2, 3, and 4 use PCI-E connectors. The specs in the documentation even state:
(2) 8(6+2)-Pin PCI-E VGA cables
(2) 6 pin + 8(6+2) Pin PCI-E VGA cables.
Notice the documentation calls the cable pci-e and VGA together.

The printing on the cable says VGA because that is the most common item they plug into. Out of hundred of thousands of users, I have only seen a few people complain that vga power versus pci power is too vague. If you read the documentation for the power supply, you will get a lot of questions answered. It’s very short at only 6 pages total.

The supplemental 6pin is not required or the same as an CPU EPS(ATX) which is why it is called supplemental. It supplements the power to the pci slots so that the power draw from the 24 pin isn’t overloaded when using more graphic cards. When using two cards, the motherboard and 24 pin are rated to run sli, and the supplemental power would only be required under extreme conditions.

The 8 Pin EPS (ATX) is required. The supplemental 8 pin or 4 pin EPS connections are not required either, unless the user is doing extreme overclocking. I doubt there is any extreme overclocking going on if the difference between VGA and PCIe cables cause this many issues.

Just a heads up, Perif connectors are actually known as four-pin Peripheral, which is a Molex connector. They are labeled Perif on the cable and power supply, even though the world knows them as molex. Figured it is best to clear that up before we get there.

Cool GTX
 
The Volunteer Members of the EVGA Forums can not see your PC, so you need to articulate what you have when requesting assistance

 
Indeed. I hope somebody at eVGA is bothering to read these posts and takes things like this into account. Clearly their documentation and/or website tool needs to be updated. 
 
 

Cool GTX
 
So, you Could use two VGA cables to power the 4 VGA positions on your GPU cards, then 1 of the single ended VGA cables for the MB Auxiliary PCIe power
 
This would leave one of your VGA points on the PSU unused.  
 

 
The GPUs have two eight pin connectors on each. The cables come with four and six pin connectors on them. In order to get all 16 pins on the GPUs going I need to use all four "VGA power cables that are really PCI-E power cables" which means no way to attach the six pins on the motherboard... which apparently we are not required to be connected. 
 
Thanks for the help guys. Clearly the website tool is dumb. It should take this into account considering I plugged in the exact setup I was going to build, complete with which GPUs, and all of it is EVGA stuff, mobo, GPUs, PS... you would think they would have this figured out.
 

Cool GTX
 
You have not mentioned which 2 GPUs you have ?

 
They are 2080 TI
 
Thanks for the help guys. I guess the solution if I want to plug that 6-pins in (that apparently does not not actually need to be plugged in) I need to get a different PSU.