Let's take a look at the MSI 990FXA-GD65 motherboard, and I will tell you, AND show you;http://www.msi.com/product/mb/990FXA-GD65.html
To the right under the bold heading - AMD 990FX chipset based,
there are views of the motherboard.
I would like you to click on the second from the Left view.
(Shows a Top view of the motherboard) It is turned to the Right.
Turn the view 90 degrees to the Left, and this is how it will be sitting in your computer case.
If you move your mouse cursor around on the view, you will see a magnified view of what the mouse cursor is on.
I will do better than this in a moment, and you will download the Motherboard Manual.
A) Requires a 24-pin ATX main power cable. The connector on the motherboard has a Locking Tab.
The power cable's connector has a Lock with a hooked end.
To ENSURE the power cable is plugged in tightly to the motherboard, the hooked end of the Lock, MUST be over the tab on the motherboard connector,
Basic example of a 24-pin ATX power cable, and it's respective connector on the motherboard,http://www.playtool.com/pages/psuconnectors/connectors.html#atxmain24
In the photo on MSI Support, the 24-pin ATX main power cable connector on the motherboard, is on the bottom of the motherboard under the Blue, and Black ram memory slots. It is Black in color.
B) Requires an 8-pin EPS +12 Volt power cable. This power cable provides the 12 Volt power needed for the motherboard.
(DO NOT confuse it with an 8-pin PCI-Express power cable. More on this later)
On the motherboard JPWR2 should be printed next to it.
In the MSI Support view, it is at the top RIGHT corner of Military Class.
Black in color, 8 socket holes.
Basic example of an 8-pin EPS +12 Volt power cable, and it's respective connector,http://www.playtool.com/pages/psuconnectors/connectors.html#eps8
The 8-pin EPS +12 Volt power cable was brought out, to replace the 4-pin ATX power cable.
The Yellow wires you see are 12 Volt wires.
The 4-pin ATX power cable has TWO Yellow 12 Volt wires. (And two Black ground wires)
The 8-pin EPS +12 Volt power cable has FOUR Yellow 12 Volt wires.
(And four Black ground wires)
As more power was required from the motherboard, the 8-pin EPS +12 Volt power cable was brought out, to replace the 4-pin ATX power cable.
C) IF, you are using a graphics card, the motherboard requires a 6-pin PCI-Express power cable ALSO.
This power cable provides more power, to the motherboard's PCI-Express x16 graphics expansion slots, (2)
[ To regress for a moment, you have TWO PCI-Express x16 graphics expansion slots, and TWO PCI-Express x1 expansion slots.
The PCI-Express x16 expansion slots are used for a graphics card.
The PCI-Express x1 expansion slots are NOT. They do not require additional power, either ]
1) IF, your graphics card requires an additional power cable plugged into it, USE IT.
Even with a 6-pin PCI-Express power cable plugged into the motherboard.
2) IF, you do not have the additional power cable, from your Power Supply for your graphics card, AND are using a power adapter cable TO the graphics card, make SURE you use the required amount of 4-pin Peripheral power cables, to that power adapter cable.
Look at a 4-pin Peripheral power cable,http://www.playtool.com/pages/psuconnectors/connectors.html#peripheral
You will see it has ONE Yellow 12 Volt power wire. (Red is 5 Volts, Black wires are Ground wires)
Using a 4-pin Peripheral power cable TO 6-pin PCI Express power adapter cable, the 6-pin PCI Express power cable requires TWO Yellow 12 Volt wires,http://www.playtool.com/pages/psuconnectors/connectors.html#pciexpress
A) You have to have an 8-pin EPS +12 Volt power cable.
B) Use a 6-pin PCI Express power cable also, if you are using a graphics card.
C) Use the power cable/s needed for the graphics card, IF it requires one.
On the first link above to the MSI Support website, hover your mouse cursor on the Downloads tab.
In the drop down list that appears, left-click on - Manual.
Drop down to the bottom file, and left-click on the blue - E7640v3.2.zip
This is a Zip file. After you click on the file name (E7640v3.2.zip), a small window will come up on the right.
Click on Save File. In the small window to the left that comes up, write down the wording at the top. This is where the zip file will download to.
Desktop, or My Documents, or Downloads.
[ If you are using a computer with Windows 7 on it, it is
Desktop, or Documents, or Downloads ]
Go to where the file is, DOUBLE-click on it. On the far left side click on
Extract all files. Then click on Next, Next, and Finish.
In the last window DOUBLE-click on the file name. (Next to the Adobe PDF icon)
For additional questions please post in a Comment.