I don't know if this is a bug from PR or from CC but your cables will connect to every side of a computer except the bottom. They just refuse to get signal from or connect to the bottom of the computer.

Clarification.

Framed wires (insulated or not) will attach to every side of a computer except the bottom.

Framed Bundled cable will connect with every side, including the bottom

This is intentional (or unintentional) by @dan200 then. Redstone wires follow standard vanilla redstone connection logic. So the computer blocks are saying that there is no redstone connection at the bottom.

Ok, I'll report it on the CC forums, see if its a bug or intentional, either way if that's true, I consider it closed from your end.