That would be for an AOpen AX4SPE-UN motherboard, because it has a Socket 478 processor socket.
I had it happen to an old mobo in the past, with a Socket 478 processor socket; and no clips.
I used a straight piece of coat hanger, and went from hole to hole, on one side.http://www.ebay.com/itm/P4-Socket-478-Intel-CPU-Retention-Retainer-Bracket-/140647148266?pt=US_Fan_Heatsin_Brackets_Accs&hash=item20bf392aea
Had a slight bend in the middle, and this bend went partially across one side of the finned Heatsink.
Small piece of coat hanger again, on the other side.
Cut to the right length, and with the correct bend, the two pieces of coat hanger, put even pressure down on the finned Heatsink.
Problem is they twisted. The pressure on the bent part against the Heatsink, made them want to spin up away, from the Heatsink.
So I added a piece of coat hanger on each side, to keep the side coat hanger pieces from twisting.
Hard to explain, and looked like something from Dr.Frankenstein's laboratory.
(Too much pressure, and it will break the plastic retention bracket on the motherboard.
Not even pressure on both sides, and Heatsink will not sit flat on Processor. This = No.
You just have to 'dial it in', (Coat hanger pieces), or use the correct part/s)