I tried to unplug the pcie power and the pc could start but couldn't boot
I plugged the pcie power again but the pc couldn't start.
I tried another vga (6800gs) with pcie connector and the pc starts normally.
I have a noname brand psu and connected two ide power to a pcie power adapter and connect it to the pcie power of the 4850 the pc could start and the 4850 and the 4850 fan was blowing fast but the pc couldn't boot.
I installed the 4850 to another pc but with poor psu and the same thing happened again.
I don't know if the problem is in the psu or the pcie connector of the 4850.