user65894: I want to mount an Arduino Pro Micro inside my PC, hooked up to the PC's USB.
I don't want to have external cables for this, but have it neatly cabled inside.
My motherboard has USB connectors with 9 pins (5+5 grid, 10th pin key), like these:

These connectors would take a cable that looks like this:

But how would I connect this to the Arduino that has Micro USB?
I've been looking everywhere, but 9-pin USB to USB Micro does not seem to exist?
The closest I could find is a cable that goes from USB micro to a 5-pin header:

What is the preferred way to hook up an Arduino Micro with internal cabling?
Why does the 9-pin to USB-micro not exist?

user71575: @Bram, @jsotola is highlighting in the comments that the example photo you show with a 9 pin keyed  two row connector has two usb cables connecting to it. USB connections often have four wires each. The standard wire color coding is:

(Source Wikipedia - USB)
Board manufacturers are often looking for a simple way to connect multiple panel mount USB ports to the PCB and this could have been a cheap and convenient way to connect two USB ports per pcb connector.
Some suggestions:

Research the specific motherboard online to see if a schematic or connector layout is available. It’s quite likely to be laid out like this:



Experiment by making your own connector, and use a multimeter to figure out which are the power and which are the data wires.
If the old USB ports which used to connect to the PCB are still available, investigate further until you’re more confident about how they were wired.
An adapter may help you experiment further to understand the PCB connections further.



A micro-USB breakout board may help you experiment with connections on the Arduino side.



65894: <p>I want to mount an <a href="https://wiki.keyestudio.com/Ks0249_keyestudio_PRO_MICRO_Development_Board" rel="nofollow noreferrer">Arduino Pro Micro</a> inside my PC, hooked up to the PC's USB.</p>
<p>I don't want to have external cables for this, but have it neatly cabled inside.</p>
<p>My motherboard has USB connectors with 9 pins (5+5 grid, 10th pin key), like these:
<a href="https://i.stack.imgur.com/LGHlE.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/LGHlE.jpg" alt="motherboard" /></a></p>
<p>These connectors would take a cable that looks like this:</p>
<p><a href="https://i.stack.imgur.com/QehJo.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/QehJo.png" alt="9pin cable" /></a></p>
<p>But how would I connect this to the Arduino that has Micro USB?</p>
<p>I've been looking everywhere, but 9-pin USB to USB Micro does not seem to exist?</p>
<p>The closest I could find is a cable that goes from USB micro to a 5-pin header:</p>
<p><a href="https://i.stack.imgur.com/qqPXH.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/qqPXH.png" alt="5pin cable" /></a></p>
<p>What is the preferred way to hook up an Arduino Micro with internal cabling?</p>
<p>Why does the 9-pin to USB-micro not exist?</p>
 71575: <p>@Bram, @jsotola is highlighting in the comments that the example photo you show with a 9 pin keyed  two row connector has two usb cables connecting to it. USB connections often have four wires each. The standard wire color coding is:</p>
<p><a href="https://i.stack.imgur.com/f1YTv.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/f1YTv.jpg" alt="usb wiring Colours" /></a>
(Source <a href="https://en.wikipedia.org/wiki/USB?wprov=sfti1" rel="nofollow noreferrer">Wikipedia - USB</a>)</p>
<p>Board manufacturers are often looking for a simple way to connect multiple panel mount USB ports to the PCB and this could have been a cheap and convenient way to connect two USB ports per pcb connector.</p>
<p>Some suggestions:</p>
<ul>
<li>Research the specific motherboard online to see if a schematic or connector layout is available. It’s quite likely to be laid out like this:</li>
</ul>
<p><a href="https://i.stack.imgur.com/QlwDj.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/QlwDj.jpg" alt="enter image description here" /></a></p>
<ul>
<li>Experiment by making your own <a href="https://www.ebay.com.au/itm/Single-Double-Row-DuPont-2-54mm-Connector-Plug-Housing-Shell-1-10Pin-2-3-9Pin-/264226603708?mkcid=16&amp;mkevt=1&amp;_trksid=p2349624.m46890.l49286&amp;mkrid=705-154756-20017-0" rel="nofollow noreferrer">connector</a>, and use a multimeter to figure out which are the power and which are the data wires.</li>
<li>If the old USB ports which used to connect to the PCB are still available, investigate further until you’re more confident about how they were wired.</li>
<li>An <a href="https://www.ebay.com.au/itm/Single-Double-Row-DuPont-2-54mm-Connector-Plug-Housing-Shell-1-10Pin-2-3-9Pin-/264226603708?mkcid=16&amp;mkevt=1&amp;_trksid=p2349624.m46890.l49286&amp;mkrid=705-154756-20017-0" rel="nofollow noreferrer">adapter</a> may help you experiment further to understand the PCB connections further.</li>
</ul>
<p><a href="https://i.stack.imgur.com/h41YI.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/h41YI.jpg" alt="enter image description here" /></a></p>
<ul>
<li>A <a href="https://www.ebay.com.au/itm/USB-Type-B-Micro-B-Male-Plug-Receptacle-Breakout-Module-Board-for-/192267601843?mkcid=16&amp;mkevt=1&amp;_trksid=p2349624.m46890.l49286&amp;mkrid=710-127635-2958-0" rel="nofollow noreferrer">micro-USB breakout board</a> may help you experiment with connections on the Arduino side.
<a href="https://i.stack.imgur.com/tHAEz.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/tHAEz.jpg" alt="enter image description here" /></a></li>
</ul>
