Arctic silver 5 is technically very slightly capacitive, which means it's very very slightly conductive. That said, I've been using it on my A64 and it's cause no trouble whatsoever. Not recommended for things like RAM though.
If conductivity is a worry for you any way, go with arctic silver ceramique, as it's not even slightly conductive. Pretty good stuff too.
Intel's stock thermal interface material is actually quite good. AMDs I'm not sure sure about. Either way, the real problem is that those pads are only good for 1 use. If you have to remove the heatsink for any reason, they're no good anymore and need to be replaced.
Chips with internal liquid cooling would likely cost a fortune, taking up valuable die space You'd almost certainly find it more cost effective to just fill your case with mineral oil.