Any heatsink compound is fine. Arctic silver is going to be way better than what the factory put on there. You'll need to clean the old compound off completely before putting on the new arctic silver. Arctic silver also makes a cleaner to remove old compound. It's what i've used when i wanted to remove old compound.

Just remember that Arctic silver compound is conductive so be extra careful not to get it anywhere and don't use too much to where it's spurting out the sides. You only need a very very thin layer.

Put a bead or two about the size of a grain of rice where the flat faces mate together.

Once you mate them don't lift them apart again. It creates voids/air bubbles and slows down the heat transfer. If you have to take them apart to re-position them, clean off and start over.

I don't think those generate enough heat that you need to be really picky about it.

Always make sure to clean the old junk off before applying new compound.

Best procedure is to use heat sink compound and tighten bridge to the heat sink before you solder, so that there is no unnecessary stress on the legs/solder/traces.

Don C.

Not sure what you mean by a "floating heat-synk" this heat sink should be secured with screws from the bottom side of the power board. It should not be possible to move this heat sink into the position shown in your picture without removing the power board and loosing the mounting screws.

As for your thermal grease, you can use anything you have lying around, just don't use thermal conductive epoxy

BEST PRACTICE: Since this heat sink is used for two components, its best to have the heat sink secured to BOTH parts BEFORE they are soldered to the board...this is the only way to ensure a proper component to heat sink mating.