It sounds like a heat issue. The fan(s) usually spin up do to heat build up as a way to cool the psu down and not bu controlled by how much power is being consumed. Have you tried running the computer with the side off the case? You should also be able to hold the psu outside the case while still connected and then power your computer up. That way it's in a cool environment and shouldn't be attempting to cool itself down by spinning up the fans.
now do i have to buy another powersupply or what must i do because i dont realy know because i dont understand the psu ,cause' all i remember that day i was trying to reset bios password with the jumper than i suddenly placed it somewhere frm there it started doing that even if i place it at its original place it does the same the jumper