Rounded cables are a piece of cake

ROUNDED IDE cables can significantly improve cooling inside your case, by offering less obstruction to the airflow. There are many rounded IDE and floppy drive cables available commercially, but they are often sheathed with thick plastic, them difficult to route, and are not always available in suitable lengths. Of course, they also cost money.

Making your own is not hard, I have been using these methods since the days when rounded cables were not available commercially.

Separating the Wires
You will need a scalpel, craft knife, or small and sharp penknife for this, and a piece of cardboard or a cutting mat to work on. Run your knife between the wires you want to separate, and make a cut. You don't need to cut all the way along the wire, just make a cut about a centimetre long, then insert a fingernail and peel the wires apart. This minimizes the risk of cutting through a wire, or exposing a conductor.

80 conductor ATA66/100/133 Cables
These are the very stiff cables used by modern hard drives. They have twice as many wires as the older ATA33 cables, because each wire that carries a signal is matched with an earth wire next to it, which reduces interference between the wires. Obviously, separating the wrong wires may cause problems, especially with longer cables.

The best way to round them off is to separate them into eight strands of ten. Start counting from the red wire, make the small cuts between the wires in the appropriate places, then peel the wires apart when you are sure you have got it right. The small wires are very difficult to count, so check carefully.

The eight strands of ribbon can now be tidied up by stacking them together in a square shape, and holding them together with a piece of tape wrapped round the bundle every few inches. The resulting cable is easy to route, because when you bend it in position, it stays there.

Floppy drive cables
These are the simplest cables to round. You can separate each and every strand of wire if you like, because there are no worries about interference with such old technology. Once the strands are separated, put a twist in the cable to hold all the wires together in a round bunch, and then secure it with tape or zip ties.

You can also take the opportunity to chop off the unnecessary second connector if you like. Use a pair of very sharp scissors for this, because you need to cut the wires as cleanly as possible, to avoid shorting them out on each other. This may make your computer recognize the floppy drive as drive B, but if you enable the "swap floppy drive" option in your BIOS it will change back to A.

40 conductor IDE cables
These are the older IDE cables, which are still often used for CDROMs. The best way to round these is to separate every other wire, leaving them stuck together in pairs. You can then bundle them together with zip ties, or tape. You can even wrap electrical tape along the entire length of the cable.

The picture below shows an 80 conductor IDE cable on the left, and a 40 conductor IDE cable in the centre, both rounded with the methods described in this article. On the right is a commercial rounded IDE cable for comparison.