It is kind of troubling to see how few people actually use Zalman Super Thermal Grease. On paper it shows the same performance as Shin Etsu. The catch is, it has consistently taken about a week to fully set in (running at full load it might take 4-5 days).
The first time I applied it, I was pissed. I would install the HSF, wait a few days and get pissed because my temps did not fall like the review said they would. After reseating over 5 times (still on the same bottle) I came to the conclusion that the stuff sucked.
To my surprise, the morning of the 7th day I woke up and checked my temps and they had fallen 3-4C overnight. I check my fans and my ambient to make sure that was not the culprit. Both were the same. Over the next 2 days I got another 2-3C drop and I got better than expected results.
The reviews of STG are always wrong imo. It says "non curing" formula on the package but it also says that it take 7 days to see optimal results. I have not been able to get it to work any faster than 5 days. I wiki'ed
the advantages of having a grease over ceramic for thermal transfer and I found that there are advantages to both. The grease however never fully hardens. It says in a grease form even after months of torturous heat. Since it is a liquid and stays a liquid it gets into all the little microscopic crevices of the metal to transfer heat.
I have used AS5 before and all I can remember is what a nightmare it was to clean up; ugh! STG is quick and easy. I use a paper tower and dip it in alcohol. I wipe from the edges to the center to keep the edges from bleeding over then wipe it clean. It is not sticky in anyway. No scrubbing required.
If it yields better temps, it is easier to apply/clean-up AND you get 10-12 uses out of a bottle, it is definitely worth a try.