Do all USB ports provide the same amount of power?
I have a laptop with 4 USB ports. Do laptops' ports have the same amount of power? Or they are just sharing certain amounts of wattage (all 4 ports), which could mean, its not good to have it all (4 ports) plugged-in by devices simultaneously?
3 Answers
This depends on if the hub supporting the USB ports is powered or unpowered. Generally, internal USB hubs on laptops and desktops are powered, which means that they each provide 5v and 500mA (for USB2) to each port. Most external USB hubs are unpowered, which means that the devices connected to it must share the available current. If you have an external USB hub that has a wall adapter that plugs into a power outlet, then that USB hub is powered and can provide full power to each of the ports.
Depends on the laptop. Typically, two ports are paired up on one hub and split a max amperage limit. So if that hub was capped at 2A, the two USB devices connected to it would not be allowed to draw more than 2A total. As to your specific laptop, I have no idea if all 4 of your ports are on one hub, or what your wattage limit would be. You never got specific on the make and model.
If all 4 USB are plugged-in simultaneously to the laptop,
Basically it will just consume more watts from the power supply,
Because each of them is consume individuale power from the power supply and calculation bandwith from the cpu.
If you will try to plugged-in A HUB (of 4 to 1 USB for example), It will work differently.
All of the 4 usb will consume the same amounts of watts from the same connector.
So you will be limited to to the cpu bandwith and/or the number of the usb devices you can use.
