The 24 pin thing is a bit confusing. One mboard I have specifically says just use a 20 pin, don't need the other 4.
But it didn't work. Made up a 4 pin to squeeze in at the end of the socket. Works fine like that.
Back to your pal's mb. Did you connect the 4 pin (two black two yellow) to the second power connector on the board? (Known as the P4 plug btw)