Dell Optiplex 740 (Internal USB port) USB1

I've recently purchased device:       Siig USB 2.0 Bay Media Card Reader 63-in-1
Link here:

My computer is an OptiPlex 740 Dell Minitower

Here is the layout of the motherboard taken from dell web site:

Link to image:

#12 is labeled in the legend (not shown here) as internal USB (USB1)

Now here is my issue. On the box it says" Connect directly to a USB 4 pin adapter"

The connector looks like this: Link to image:

However the USB port on the motherboard look like this: Link to image:

and I'm left  without a clue as to how should I plug-in the connector (it's not exactly only one-way fits deal)

and of course the last thing i wanna do is to fry my card reader or even worse my motherboard.

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Does the connector on the cable have a clip to fit the connector on the board? If so you should be ok to skip the last pn on the board, and just use the 4 pins that match the cable.
Anti-MhzAuthor Commented:
the connector is as pictured in the photo: (2nd picture from the top)

Heres what the manual for the card reader says

"Note: The 4-pin USB connector is keyed to plug into the 4-pin row of USB Pin-out Header.
Make Sure that the Red wire is plugged into the +5VDC pin on the header."

The manual also says  to match up +5VDC Pin 1 to USB Cable Connector Pin 1.
That leaves out 2 choices really.  Also 50% chance of damaging something.

You're going to have to plug the connector onto the top row. The 5V end of the plug will go into the top row pin closest to the capacitor. The ground pin will go in on the 4th pin on the top row (one pin away from the pink thing). I hope this helps.

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i'm not sure that is the +5 V volt.
i see one way to make sure : power the mobo up, and measure which pin is + 5V, and which is ground of both outermost ones !
i agree with nobus.
this is only way to figure out which ping is +5v and gnd.
by examining the last image you attached of usb header.
there are five ping 1 to 5 from left to right..
power up motherboard > set multimeter to dc voltage measurement of range 1-20 vdc. > touch the red terminal of multi meter to pin one and black one to pin 4.
if you get  - 5 v reading on multimeter screen. the 4 pin is 5vdc and 1 pin is GND.
if you cant get readings for pin 1 and 4. 
do same procedure for pin 2 and 5.

i assuming you are using standard digital multimeter. and have some knowledge of electronics systems voltage / current measurement and precautions.
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