As someone who has worked with high current DC power supplies, I feel I should point out that a 7200 RPM drive pulls 3 to 7 Amps when spinning up. With 10 drives in your cable, you have the potential for 30 to 70 amps to be passing through the lower segment. Those wires are usually 18 or 16 gauge if you are lucky, and you are exceeding the safe amperage rating for that by 200 to 300%. Those wires should really be more like 10 or 8 gauge.
Now, obviously, you aren't pulling that load all the time, and there is a duty cycle involved, but those wires will be trying to carry that current if you spin up all the drives at once.
Not to mention that Molex drive connector is rated for about 8 amps if it's a good one, and you could be asking it to do 70..