Symptoms

When an external USB 2.0/3.0 hub is used with keyboard/mouse, repeated keystrokes and slow mouse movements may be observed. #1: Typing "123456789" on the keyboard, some characters may be lost, for example, it shows only "1235789."#2: The keyboard stops working or bursts a series of characters.#3: Mouse clicks do not work, or mouse cursor movement is slowed. Observed in UEFI Shell mode, the CPU does not act until the user inputs a command.

Cause

AMD BIOS default setting "Enable DF C-State" on AMD 2-Scoket Server CPU system.DF C-states help reduce power consumption by allowing parts of the Data Fabric to enter low-power states when full performance is not needed.When in DF C-state, the CPU can enter a lower-power states while idle, but a delay occurs when transitioning back to full-power mode. This causes the CPU completion response time to be longer.This issue only occurs with External USB Hubs and system idle mode, using a KVM or direct connection to USB ports works fine.

Resolution

Fix:Target fix date: July 2025Workaround: BIOS Setup menu - System BIOS - System profile settingsChange the system profile to "Custom."Change DF CState to "Disabled."

Support Cases