How to connect 127 USB devices to your PC. Kinda...
Who hasn't wondered or dared to dream exactly how many USB devices you can connect to a single PC? Or how many unpowered USB hubs you can daisy chain? Or what about daisy chaining powered USB hubs or the limits to slotting in USB controller cards?
The possibilities are almost endless, with the emphasis on almost. Because YouTube channel Linus Tech Tips has the answers to all these questions, and more.
For reasons that we won't bore you with, the theoretical limit for USB devices connected to a single PC is 128, but the practical limit is one fewer. At least, that's the, er, theoretically practical limit.
In actual practice, it typically turns out to be far fewer. That's usually down to the USB hubs being used to expand the number of ports and how they're connected.
In reality, pretty much every physical USB hub actually contains multiple internal hubs. And however many hubs there are, you can usually double that ostensible number because each hub in any reasonably recent device can typically run in both USB 2.1 and USB 3.1 modes.
The rough upshot is that if you attempt to daisy chain three of any given hub, Windows will get cranky on you and inform you, «Error. Too many USB hubs. A hub will not function when it's connected more than 5 hubs away from the root port.»
In simple terms, each hub acts like a double hub, so three of them daisy chained is actually six hubs away from the system root USB port. You'll also very quickly run into power delivery problems using unpowered hubs. So, there's zero chance of hitting 127 devices using unpowered hubs.
Even using larger 16-port powered hubs connected separately to the PC can create problems, because such physical hubs, again, contain numerous internal USB hubs.
So, to really
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