What on earth do they put on the NB heatsink?

[chz]

Okay so, yesterday i decided to finally switch out the stock paste to some arctic silver to get my NB temps down. I popped it off easily and turned it around, and what do i see? Some weird yellow stuff, hard as concrete, barely any of it left on the NB, all of it intact on the heatsink itself o_O

What the .... was that crap, i know the mobo is high quality otherwise and the heatsink is good, but the paste was a serious disappointment. Furthermore my load temps went from 55 (bios 100% fan speed @ 55C) to 44C load. Quite a difference with just a little paste...