Laptops with 3-4 internal HDDs and 1-3 CD drives? We call those desktops in this part of the world!
Ahh a slip of the fingers
Mizture
If you're talking about USB devices, then yes, its a well known fact that the motherboard produces a finite amount of current on the USB ports (the exact amount varies by manufacturer). It is also a well known fact that on some motherboards some ports are high draw and others are low draw, and if you happen to plug a high draw device into a low draw port, you won't see much.
If an optional external power adapter is available for your caddies, try that. Otherwise a powered USB hub. Quite honestly if your caddies are for 2+ drives and you've got drives in all the slots, you would be better off with external power adapters anyway.
Perhaps an interpretation but all my caddies have externaL power. I assume that was to power only the spinning mechanisms and that the USB slot had to handle any current draw that moved the bits and bytes around the motherboardl. My 3.0 USB board uses the same power connectors that all the internal hard drives work off.
I assume that is 5 volts or so and that by the time it runs several feet to the caddies it may have dropped.