Hmh. The power supply is 4 years newer than the mainboard, and it works fine. Also have both USB ports 5V.
Maybe this problem is unsolvable, but at least now i know how to mount with Vector Linux, and can mount devices when they are connected from the beginning.
And it's not that
important to me because i don't use pendrives/cams very often. Anyways, thanks for your help!