Liquid Metal Thermal Paste

[BGP Spook]

Capacitance is not really a property paste could have, particularly if its noncoductive. If you mean they'll be some compacitance between teh die and the heatsink, thats true of any paste, so don't worry about it.

[offtopic]
Sorry for OT:
AS5
If you follow the link and look under the heading "Not Electrically Conductive:"
You will find this:

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.)

Quoted from the Arcticsilver website.
[/offtopic]

I wonder what that gray fluffy stuff is.