Hello I'm going to attach a heatsink to my  vert very old ATI Rage 128 (16VRAM) graphiccard. I found a reather small heatsink that will to the job perfectly. I'm going to use ordinary thermal compound but I wonder how will the heatsink hang-on to the card. If I got it right the thermal compound gets stiff after several hours or days of use. But until that day it gets stiff will the heatsink hang-on to the card? The card is located in an old B/W G3 so it's going to be hanging upside-down. I'm afraid that the heatsink will fall off since it's just attach with thermal-compound. Should I be afraid?