Power supply through PCI-E during power-off
Power supply through PCI-E during power-off
Current motherboards include a BIOS option that allows USB charging when the system is off, letting you charge your phone without the CPU using power from the OS. There appears to be a power management feature on the board itself that handles this. I’m wondering if PCs can supply power to PCIe devices even when the system is powered down. Is there a specific BIOS setting for this? Do PCIe components signal their needs directly, or does the CPU adjust power levels? Would this capability need a BIOS update, or should the board already support it with extra hardware and routing? Are there low-power modes that work without relying on the operating system being idle? I’m trying to figure this out without checking online resources.
Certain graphics cards feature a small indicator light that signals whether the proper 6 or 8-pin PCIe power connection is present, and this light remains lit even when the computer is powered down, indicating the PCIe slot continues to supply power to the card while it's off.
The RGB lighting on the motherboard remains on during shutdown, indicating some activity in the MB. It seems the manual doesn't provide clear details. You might consider using a Raspberry Pi or similar device via a custom board to avoid needing power adapters. Edited February 18, 2020 by MuffinDealer grammar
USB equipment can operate when the computer is in standby mode since the power unit includes a compact 5VSB supply. This smaller unit powers devices while the system remains off, allowing you to keep your peripherals running and enjoy RGBarf for nighttime visibility. PCIe connections either link directly to the CPU or reach it through the chipset. When the system is off, no data transfer occurs. From a power standpoint, PCIe ports can supply 3.3V up to 3A (about 10W) or 12V up to 5.5A (66W), totaling around 75W. However, since the PSU only provides 5V in standby, it's unlikely you can power any PCIe devices while the machine is off—unless the motherboard reduces the voltage. This capability seems mainly for Wake on LAN features, which are uncommon in standard boards. 5VSB ratings typically cover 10-20W, so most PCIe cards won't draw much current. In short, you shouldn’t power PCIe devices when the system is off. I’m not sure about Asus models, but usually you can disable RGBarf or adjust the ErP setting in the power menu. The Raspberry Pi runs via a micro USB adapter delivering 5V 2A; it might work with a regular charger if you confirm the voltage rating. Try connecting it to the back USB ports and see if it powers on.