127 USB Devices on a Single PC? Yes, It’s Possible, but Not Simple!

TECH NEWS – Ever wondered how many USB devices you can hook up to a single PC? Or how many USB hubs you can chain together? And what about the implications for performance and stability? Linus Tech Tips sought answers on their YouTube channel, and the results are intriguing.


USB, or Universal Serial Bus, is a standard that allows devices such as keyboards, mice, flash drives, external hard drives, and webcams to be connected to a PC. There are multiple versions of USB, offering different speeds and power capacities. For instance, USB 3.1 can deliver data transfers up to 10 Gbps and a power of 100W.

However, USB isn’t limitless. In theory, one can connect up to 128 USB devices to a PC, but in practice, it’s 127 due to one port being reserved by the PC itself. Yet, even this might be unachievable depending on the USB hubs used to expand connectivity. USB hubs aren’t just mere splitters; they often comprise several internal hubs operating separately in USB 2.1 and 3.1 modes. If you plug three hubs into one another, you’re already six hubs away from the PC, surpassing the Windows-permitted five-hub limit. You’d then be greeted with an error: “Too many USB hubs. A hub will not function if it’s more than five hubs away from the root port.”

Power can also be an issue. Without their power sources, hubs may quickly drain the power they draw from the PC, rendering them non-functional. High-capacity powered hubs with up to 16 ports can be a solution, but they too can pose limitations due to their multiple internal hubs restricting the number of connectable devices.

The ideal workaround would be using a motherboard laden with numerous PCIe slots to accommodate USB controller cards. This setup would circumvent chaining USB hubs and allow devices to connect directly to the PC. But even then, hitting that 127 mark isn’t a walk in the park. Simply using flash drives wouldn’t suffice as you’d run out of drive letters. A combination of keyboards, mice, and other USB gadgets seems more plausible.

Linus Tech Tips achieved a setup of around 110 USB devices using about 20 flash drives, a bunch of keyboards, a basket full of mice, and a motherboard packed with USB cards. However, they hit a wall – potentially due to the drives. They couldn’t definitively gauge the impact on the PC’s performance or stability, but it’s safe to assume it wasn’t favorable.

So, to the burning question of how many USB devices one can connect to a PC – the answer is a lot, just not as many as we might desire. Attempting to max out isn’t advisable, as it’s a recipe for unnecessary complications. But for those driven by sheer curiosity, check out Linus Tech Tips’ experiment video.

Source: PC Gamer

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