Only thing I can think of you are Using an Motherboard without a High speed SATA Drive (The Hard drive has a slim red ribbon cable which plugs into an "L" Shaped socket the Older IDE/ATA drives have the big ribbon cable ,and the Drives are "Jumpered" but the SATA Drives are Jumperless and Do not need preparation before use The motherboard Needs to have The spare plug fitted
As you saw it will run on the old board But there is no Socket provided for the P4/12V Plug. Found this off an American computer part stores page which may help with the Mystery