no they are not!
I was able to drill a hole, but unfortunately the GND pins on the IDE cable ... are all connected,
for a 40 wire
IDE cable, it its just an IDE cable, wires are not connected between each other, unless plugged into an actual device that connects the wires together externally to the actual cable.
As said below a "80 wire IDE cable" is not a normal IDE (isolation displacement) cable, it is a specifically manufactured product that overcomes the transmit line problems of a normal 40 pin IDE cable by giving each wire its own ground return wire, and in the process it connects all pins used as GND in a harddisk interface cable together! it cannot therefore be used with a PI!