They're fairly secure, I assume you worry about them falling off. They will not. Load and idle before and after:
Before (ambient ~27c)
Keep in mind this was with some crappy SilenX brand fan that had almost no static pressure. Well, i replaced that with a Zalman ZM-F3 (great fan, for a great price, sleeve bearing though
) and lapped my heatsink and they are now:
Thermal paste = MX-2
With an ambient of about 23c (its colder in my dorm). It was my first lapping attempt so i might not have done perfect on it, might fix that when I get my lapping kit next month
, I'll try and take pics too.