ATX 24 pin to 24 pin mini modification

I have a hp slimline motherboard which i decided to move it into a bigger case. With the bigger case i need a standard size power supply but the 24 pin connection of a standard power supply is to big for my 24 pin mini motherboard. Unfortunatly there are no 24-pin-to-24-pin-mini adaptors in my area, so i was wondering if it's safe just to change the standard male connector unto de smaller male connector of the psu. They both look alike, with the only diference that one is smaller than the other, so could i just solder the bigger 24 pin cables the same way they where on the mini 24 pin?