Your 670 scores are widdling on my 680 scores. 😡 😉
Is your 670 a reference cooler? How difficult is the 680 reference cooler to remove?
The MSI cooler is non-reference, and actually not that difficult to remove -- four screws on the back of the card, after disconnecting the fan connector. Cleaned both the GPU and heat sink surfaces with isopropyl alcohol (96%) and applied the GC-3. It's a little tricky to get a good, even application that's not too thick, has no bare spots and also not to get half of the TIM on the surrounding circuit board
🙂 , but if you're careful and don't squeeze too much out of the tube to start, it's doable.
I'm certain if you search online there will be a pictoral or YouTube or something for removal of a reference cooler, though it shouldn't be too much different -- here's one pictoral:
http://www.legitreviews.com/article/1881/4/
...so it looks to me like six screws hold the shroud on, then four on the back of the card, just like the MSI, that hold the heat sink in place.
The Gelid compound also fixed my wife's laptop overheating problem this weekend -- kept shutting down intermittently all of the time. We got the temperatures on it down from 60-80C to 40-60C, and it's solid as a rock now. Thank God someone posted an online guide with detailed photos on how to disassemble it, as I would never have figured it out otherwise -- first time I ever took one apart. The manufacturer did a horrible job applying the factory compound; there was more of it around the CPU/GPU than on it... no wonder it had such bad thermal stability.