No.

Old thread—I get it. But relevant info here nonetheless... The thermal conductivity of Liquid Ultra is far less than the nickel/copper substrate of the IHS and your heatsink, and while I don't know exactly what the thermal conductivity of nickel-gallium and copper-gallium alloy is—and thus, can't be certain whether or not any build-up will act as a thermal conduction inhibitor—a good rule of thumb is to eliminate as much thermal interference as possible and/or practical. Heat will only transfer as much as the weakest link in the conduction chain will allow it to. I re-did my de-lid fairly recently. The bottom line is, If there's any Liquid Ultra build-up on the surface, it absolutely should be removed from the heatsink and IHS, especially if you're replacing it with another material that conducts heat better than Liquid Ultra, like Conductonaut. You can tell it's build-up by letting light reflect off the IHS/heatsink surface from different angles. The build-up will be splotchy and a darker shade of gray. Polishing compound works quite well for removing the build-up. Hydrochloric acid isn't going to remove it because the build-up isn't actually a build-up per se; it's a nickel-gallium or copper-gallium alloy; the chemical composition of the bare copper and/or nickel plating has changed at a molecular level. When the build-up is removed completely, you'll end up with a one homogeneous shade of gray when light reflects off the surface at different angles. If you're removing it from bare copper, don't try to return the surface to bare copper, because like I said, some of the copper is now a copper-gallium alloy. It's only a couple of microns thick at the most, so it shouldn't inhibit heat transfer a whole lot, especially if you're about to use another compound that also has gallium in it. All you're shooting for is a smooth surface that's free of splotchy build-up. It's better to have a highly-flat surface with a little gallium alloy than an uneven surface of bare copper. On a side note, Conductonaut is legit. Liquid Ultra kept my temps from going over 65° C; after redoing with Conductonaut, stress-testing can't push them over 58° C. That's an i7-6700K overclocked to 4.8GHz...

It worked.. I can't believe that ****ing worked.. I'm beside myself in disbelief.. Don't feel dumb. Microsoft troubleshooters aren't worth dick 999,999 times out of 1,000,000. They're there to humor (or console) those otherwise helpless users that have no access to administrator-level resources.