USB ports occasionally lose power if both USB-A ports are in use

GamingSeargent · November 12, 2021

Hello, I have a MSI B550 Tomahawk within a Fractal Design Meshify C. I have noticed that when I plug things into both the ports on the Meshify C, all the USB boards (the ones on the case AND the ones on the motherboard) lose power.

This issue doesn't seem to occur when plugging the same things into the motherboard USB ports.

The things I am plugging into the case's ports are: a USB reciever for headphones, and either a IOS charging cable, or a headphone charging cable.

mariushm · November 12, 2021

Some motherboards have a fuse / protection thing that disables ports when the power drawn is too high.

This protection is typically set at around 2 - 2.5A for a pair of usb ports, so if one port does up to 2A that's fine, but if both together go above that threshold, the protection kicks in and disables the ports.

Normally, a usb 3.0 device is not supposed to take more than 0.9A of current ( 5v x 0.9A = 4.5 watts) but a lot of devices exceed that amount.

Also, you should be careful about what cables you insert into usb ports. The cable that comes with a usb charger for a phone may have the data lines wired in some specific way to tell the phone to charge at a higher current, or the data lines may even be shorted together (something that the usb controller may not like and may shut down to protect itself)