I realize that this posted problem is over 4 months old, but in the interest it may help someone;According to Compaq this is the motherboard used in the Evo D510 Convertible Mini-Tower,
http://www.ebay.com/itm/MotherBoard-Compaq-Evo-D510CMT-Pentium-4-2-4GHZ-512MB-Ram-Heat-Sink-/120814069962?pt=LH_DefaultDomain_0&hash=item1c211468caObserve the blue long female connector on the motherboard. This connector is where the 40-pin flat IDE ribbon cable for the Harddrive, plugs in.
http://www.andovercg.com/datasheets/compaq-hp-evo-d510.pdf(On the above link; it may not work as a direct link. It is a PDF file you download. In case it does not work just by clicking on it; copy it, paste it into your address bar, press the Enter key )Scroll the page down to a little more than halfway. Observe the illustration of the motherboard to the Left of the page.(Has J22, J21, P23, J20, J40, P54, above it)Look at CR1, CR2, CR4, and P5Regards,joecoolvette