Sticky thermal pads are genearly used, you can get them in varying thicknesses and sizes.
Think he means adhesive thermal pads removable whereas thermal glue isn't, in case you go back to stock cooling
Akasa Thermal Tape would be better as you can take it off again if you need to. With glue when it's on it's on for good. I used to use the Akasa thermal tape and never had a heatsink come off once it was fixed in place and I had some heavy copper heatsinks at times. It's the second one that Armageus linked to and you just cut it to the sizes that you need. Be sure to clean the bottom of the heatsink and the surface that you are applying it to with IPA to remove and left over residue.
My basket at Overclockers UK:
- 1 x Arctic Silver Alumina Thermal Adhesive (5g)= £7.99
- 1 x Akasa AK-TT12-80 Thermal Adhesive Tape= £2.99
I used that tape with a big copper heatsink I made for the vrm's on a couple of gpu's (GTX480, GTX 780) when I used to use a core only block and they never fell off. The key to it staying stuck is properly cleaning both surfaces. The stock cooler's thermal pads leave a oily residue on the chips and if not cleaned off properly the tape won't stay stuck.