Ever notice all those gold contacts on cables and connectors?
When whether it's a USB drive, an HDMI cable, or a graphics card,
they have a ton of those little pins on there. But why do they need so many?
Let's start out with possibly the most straightforward reason of all.
Power. Putting an electrical connection and a data connection on the same contact would cause interference.
So most modern digital connectors separate those onto different pins.
And then you have the fact that current needs to return via a ground connection,
meaning you need at least two connectors for power, which you see in USB-A connectors, for example.
But having tiny pins means you can only put so much current through them.
Think about how when you go and buy an extension cable, the larger ones are rated for more power than the smaller ones.
It works similarly with your electronics. So devices that need relatively large amounts of power
often spread out their power delivery across many contacts.
A great example of this is pins on a CPU. Modern processors have over a thousand pins,
many of which are dedicated to power delivery. With higher-end CPUs now drawing over 150 watts at load,
roughly the same as a 75-inch TV, it isn't hard to understand why you don't want to put all of that power
through just one little pin. He's only one pin, John!
Speaking of power, some connectors have additional pins to accommodate multiple voltages.
You can see this in the standard 24-pin power connector for computer motherboards,
which has to provide 12V, 5V, and 3.3V power.
And while most components these days run off 12V, the other voltages are still supported for any components
that still need to get the lower voltages directly from the power supply.
But there are plenty of other reasons for all those pins being there besides just power.
Part of the reason we can send so much data at once these days
is because of something called differential signaling.
Basically, each data signal is sent using two pins instead of one,
and each signal is basically the same, except one is positive and one is negative,
as you can see on this illustration. This has a few advantages over just using one pin to send a signal.
It can resist interference better and operates using less overall power,
meaning that the connection can operate at higher frequencies,
meaning more data per second. You can pretty clearly see the two differential signaling contacts on this USB connector.
Higher speed connections will often spread out their bandwidth over multiple differential pairs
in order to increase the overall amount of data that can be sent per second.
This is part of the reason USB-C has more contacts than older USB-A connectors,
and also makes up the vast majority of contacts on a PCI Express X16 graphics card.
And there are some other functions that extra pins perform outside of ensuring data gets from point A to point B as quickly as possible.
Some connectors dedicate a pin to a clock,
a separate signal that keeps the flow of data synchronized.
Others might have a pin to enable some kind of special functionality,
such as consumer electronics control or CEC on HDMI.
CEC is what allows you to control something like the volume on your sound bar
through your TV remote, and some pins simply serve as shields for adjacent pins to prevent interference,
or as presence detectors simply to let the system know that a device is connected.
So contrary to popular belief, engineers didn't put all these pins there just because they were really into making electronics look like fancy gold combs,
as disappointing as that is. Go watch this video next to find out more about why CPUs specifically have so many pins
and why their sockets keep on changing. Why?
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