Thermal Paste Showdown

[S0ULphIRE]

It's capacitive. Here's their official line:

Not Electrically Conductive:
Arctic Silver 5 was formulated to conduct heat, not electricity.
(While much safer than electrically conductive silver and copper greases, Arctic Silver 5 should be kept away from electrical traces, pins, and leads. While it is not electrically conductive, the compound is very slightly capacitive and could potentially cause problems if it bridges two close-proximity electrical paths.)

 

[C0RR0SIVE]

It's slightly capacitive, I had some bridge one those little chips on an old socket A processor once, it didn't mind it, though, it acted very odd.