I have a gigabyte motherboard and I'd like to replace the PCH's TIM with AC MX2. Is it easily possible? I have Arctic silver tim removal and surface purifier for whatever that's worth.
Is it supposed to be stuck on there or is it removed easily?
I'm not familiar with that specific chip/heatsink combo, but most heatsinks are mounted either with some silicone thermal paste or with a thermal pad. Sometimes something might be mounted with permanent thermal epoxy, but i have yet to see this (if the heatsink has some mounting mechanism, clips, screws, etc, it's not epoxy)
If it's silicone paste, it will either still be wet, or it might be dry.
If it's wet, the heatsink will come off easily, and the paste removed with your cleaner of choice.
If it's dried, you may have to do some gentle nudging and prying to get it off, and then use your cleaner of choice (and maybe VERY light scraping)
If it's a thermal pad (doubt it, this is usually only used in laptops and heatsinks that cover multiple components) then it will come off easily, and the cleanup will be easy too. However, you want to confirm the heatsink and chip actually mate and don't hover. If they leave a gap for the pad to fill, then you should not replace this with any paste or grease, but only another pad (or maybe some aluminum shim if your feeling lucky).