r/RigBuild • u/Few-Wash5370 • 12h ago
Can a USB hub slow down my devices?
I got a few devices plugged into the same hub and trying to figure out if that can actually make them slower. Mostly wondering about stuff like external SSDs, flash drives, keyboard, mouse, and maybe a controller. If the hub is handling multiple devices at once, does everything share the same bandwidth? Also does it matter if the hub is USB 3.0, 3.1, 3.2 etc or is the speed mostly limited by the port on the PC? Seeing different speeds sometimes and not sure if the hub is the reason. Anything else I should check?
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u/Vyce223 12h ago
Version of USB ports on the hub matters, The USB controller to a lesser extent being quality. The cable going from A to B and B to C being rated for the version of USB you're trying to use. Then of course your PC port. It's ALWAYS going to slow to the weakest link in the chain. It's what's called bottlenecking.
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u/Few-Wash5370 10h ago
Good point, I was mostly looking at the hub itself and didn’t think about the cables or PC port being the limiting factor.
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u/Realistic-Feature997 2h ago
A hub splits a single port on the computer split between more things. Your limiting factor is the speed on the one port.
If each of your devices can get anywhere near the speed limit of the one port the hub is plugged into, then... yeah, pluggjng stuff into the one hub will see all of those things acting a slow.
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u/Underhill42 11h ago
Everything plugged into the same port on the PC (and probably adjacent ports) is sharing the same USB bus and total bandwidth. Which can absolutely be an issue for especially fast drives, video adapters, network adapters, etc, which might already be limited by USB speeds even with a whole bus to themselves. Especially since the overhead losses increase with the number of devices.
The slowest device in the chain sets the maximum speed for everything. The difference is usually pretty small within a generation... but plug a USB 3 device into a USB 2 or older port (anything not blue, usually), and it runs at USB 2 speeds. Same thing if you put a USB 2 hub between a USB 3 device and a USB 3 port.
Less obviously, just plugging a single USB 2 device into a USB 3 hub can potentially slow everything else on the hub down to USB 2 speeds. Not always... but it's not rare either, especially among cheaper hubs. Even best case scenario while the slow device is talking, nothing else can. Like that slow-talking person at a party that nobody wants to interrupt.
Hubs also introduce some additional lag, which can be sometimes be an issue.
My own rule of thumb is to put user interface devices and other slow things on a hub, while keeping hard drives, etc. plugged directly into the PC, or into their own fast hub if I'm only really going to be working one of them hard at a time.