Aspects of the embodiments are directed to systems, methods, and apparatuses for controlling power management states using a clock request message across a 3.3 volt GPIO pin. Systems can include a CPU root port to transmit to a platform controller hub (PCH) compliant with a PCIe protocol, a first clock request message, the first clock request message comprising a first bit set to assert a clock request transmit (CLKREQ TX assert) on a 3.3 volt general purpose input/output (GPIO) pin local to the PCH; detect that a connected device is entering into a power management state; and transmit, from the CPU root port, to the PCH, a second clock request message, the second clock request message comprising the first bit set to deassert the clock request transmit (CLKREQ TX deassert) and a second bit to assert a clock request protocol (CLKREQ#) on a 3.3 volt GPIO pin.