[Solved] Motherboard and Case Connections

dndhatcher, thanks for the quick response and description on USB Connections.
Paperdoc, thanks for the detailed explanations. Sadly my motherboard came without a manual, but with my brother's help I was able to plug the connections in place.


Hi, after struggling to try and solve this myself, I've come seeking aid. I need help determining which cables from the case connect to the motherboard and where they should be connected.

I have the following:
ASUS M4A785TD-V EVO AM3 AMD 785G HDMI ATX AMD Motherboard HEC Black / Silver Steel ATX Mid Tower Computer Case

Images for motherboard:

Cables on case:
Thicker wires:
Azalia (2x5 pin) (4th on second row is blocked)
AC'97 (2x5 pin) (2nd on first row is blocked) -- I think this has only one place it can go.
USB (2x5 pin) (1st of second row is blocked)

Thin wires:
POWER SW (power switch)
H.D.D. LED (hard disk drive LED)
RESET SW (reset switch)

Motherboard has lots of connections, you can see some in picture, but I'll try my best to list those I think are relevant:
PWR_FAN (3 pin)
SB_PWR (3 pin) (Motherboard LED is below it, 2 of 3 pins are covered with removable cap)

AAFP (matches AC'97) Think it's only place that does.
SPDIF_OUT (4 pin size but second pin is absent).
IE1394_1 (matches USB cable)
USB1112 (matches USB cable)
USB78 (matches USB cable)
USB910 (matches USB cable)
some 10x2 connection but with several places lacking a pin.

Where do the cables connect? (most importantly, the POWER SW cable). Are there any cables that don't connect anywhere? Thanks in advance to any who helps.
3 answers Last reply Best Answer
More about solved motherboard case connections
  1. USB78 is USB ports 7 and 8, thats where you should plug the motherboard USB cable.
    USB910 is for additional USB ports 9 and 10; USB1112 is for additional USB ports 11 and 12.

    IE1394 is for a firewire cable. Your case doesnt seem to have one.

    A= Audio, AAFP and AC97 should be correct.

    The motherboard manual should have a chart for that 10x2 section and the reset/hhd/power plugs should go in some of those. Getting this block plugged in correctly is both critical and often challenging.

    You should have a CPU_FAN to power the CPU cooler fan. PWR_FAN and SB_FAN are probably for extra case fans. SB_FAN could be to power a fan on the southbridge cooler (you may not have one).
  2. Best answer
    For orientation, we usually position the mobo so that the CPU socket is at the upper center. This puts the RAM sockets at upper right and the back panel connections at upper left. See your manual, page 1-7.

    First note: Make sure you plug the thicker cable for the front panel USB ports into one of the USB mobo connectors - USB78 would be fine as dnhatcher has said. DO NOT plug this into the IEEE1394_1 connector. Although it would fit, the electrical signals on USB and IEEE1394 ports are quite different, and you could damage your peripherals and/or mobo by doing it wrong.

    The four thin wires you mention all go to the connector in the lower right corner of the mobo labeled "Panel". Refer to your mobo manual on pages 1-7 (diagram) and 1-25 (details). I expect on the ends of each of these "thin wires" there are connectors that either are single little sleeves for each wire, or are 2-wire blocks. The two for the Power-On LED indicator go to the pins indicated on page 1-25, etc. The wires / connectors probably have + and - signs to indicate polarity, and so does the diagram on p. 1-25, so follow that, and don't worry. For the on/off switch and the reset switch, the polarity actually does not matter at all. For the two LED leads the worst that can happen if you plug them in with reversed polarity is that they simply won't light up when they are supposed to. If you see that, just reverse the leads for that LED at the Panel pinout.

    Your mobo manual lists 3 fan connectors: CPU_FAN (use ONLY for CPU cooler) is at the upper right of the mobo; CHA_FAN (use for case chassis fan) is at the left middle, near the rear connector panel. The PWR_FAN at the right middle, near the 5 SATA ports, normally does not control anything. It is for use with some power supply boxes that have a special wire coming out that hooks up to a mobo 3-pin fan connector. What it really is for is just to send the PSU fan's speed signal to the mobo for monitoring. Many PSU's do NOT have this signal output. I have read posts here saying that this PWR_FAN connector actually CAN be used to power a second case fan instead.

    There is NO SB_PWR fan connector! The SB_PWR label you see is for the LED next to it that lights up to show you that the Southbridge (and hopefully all the board) has power to it. Right below that is a set of 3 pins labeled CLRTC with a jumper on 2 of the pins. This is what you use for resetting the BIOS. Look up that procedure in your manual. You don't usually need it so leave it alone unless necessary. And DO NOT connect anything to these pins!

    Your mobo supports EITHER AC97 audio, or Intel High-Definition Audio (aka Azalia). Since you have both possible front panel connections, the mobo manual on page 1-27 recommends using the Azalia version for better sound output quality - if you have external units that can use these signals. The front panel sound connector is the one marked AAFP. Whichever option you choose, make sure to set your BIOS to that - see manual p. 2-15.
  3. Best answer selected by nicolasjager.
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