I recently tried connecting a 24-pin ATX 2.1 PSU to a motherboard with a 20-pin connector. I plugged the correct 20-pin part of the 24-pin plug into the socket. Nothing happened when i attempted to power up the PC.
The 24-pin PSU works fine with a 24-pin motherboard. The 20-pin PSU also works fine with an older 20-pin mobo. I have read that the 24 pin PSUs might work with the 20-pin mobos, but it depends on the particular motherboard.
Is there any way to make a 24 pin PSU work consistently with 20-pin motherboards?