Most manufacturers but more TIM on their chips than required.
It also varies by chip type ie the 680GTX is very small & needs only a very small amount & the 580GTX is a bigger chip so requires a little more.
Best to take the cooler off, clean everything up & put a little grain size blob on the chip. Then test fit the cooler, remove and check for good spread across the chip.
Also make sure you have the correct screwdrivers to remove the cooler.
nVidea now use 'thread lock' to stop the screws coming undone.
This makes things more difficult (not impossible) to remove but you must have the correct tools.
If you are doing a 680GTX, then look at the last page of my build, it may help
http://forums.hexus.net/chassis-mods...d-build-9.html