Keyboard sending some voltages to pc via its usb cable

[F4BIOD3V]

Hello guys,

Some time ago I was gifted a weird keyboard (Strike 7 from Mad Catz) and I started to test it right now.
This keyboard get powered from two sources: an usb cable to pc (that powers some rgb on the keyboard and allows the communication between pc and keyboard) and an AC adapter.
Now, when the keyboard is connected via its AC adapter it provides some backfeed voltage to my pc via its usb cable. I tested this connecting a fan to the keyboard's usb and it was spinning like if it was connected to my pc.
Moreover when pc is correctly in a shut down state and disconnected from the electric socket, when my keyboard is both connected via its usb cable and ac adapter, the mainboard's green led is correctly switched on.

The whole point is: how much is safe all this?

 

[Spinachy]

If you are unhappy with your keyboard, get rid of it, and use one that works for you. Remember that all USB ports supply 5V, so you would expect to get 5V when you connect to any end of a USB cable.

 

[Phillip Corcoran]

Don't see any such problems reported in buyers reviews on Amazon so I reckon yours must be faulty. Looks butt-ugly to me anyway so I'd dump it and buy a different one.

 

[F4BIOD3V]

If you are unhappy with your keyboard, get rid of it, and use one that works for you. Remember that all USB ports supply 5V, so you would expect to get 5V when you connect to any end of a USB cable.

It seems fair if the cable sends power from pc to keyboard but should the opposite be not allowed? I mean it seems a bit unhealthy for my pc being "5V" powered from my keyboard..