Antec's nano diamond thermal compounds are superb. Especially when you can tell the missus you have bought a box of diamond. I've tested the formula 7 most of all and we use that on almost every PC we ship. As a minimum we use Formula 6 which is excellent but does not stand up to such temperature extremes. That sentence does not really do Formula 6 justice since its got a very wide stable temperature band and excellent cooling.
I've tested it in my workhorse PC which has an AMD FX-6100 six core CPU, 8GB RAM, a GTS 250 and two OCZ SSDs on an ASUS M5A99X EVO motherboard. All at stock settings. I was previously using Arctic silver as my thermal compound before discovering diamond based compounds and these were excellent. The diamond suggests that best performance is achieved after a few thermal cycles so you need to get your PC up to temperature for a while and then let it cool a few times. I initially checked the temperature was OK and then checked back after a week to see how it had gone. It was 4°C Cooler.
That may not sound like much but I was already using a good branded silver based compound so to get such a drop was very impressive. This temperature change was under light loadwith the temperature in the low 30s. I will consider in the future running some more extensive tests and trying it under heavy load while overclocking where the difference would be much larger. I've checked some more detailed reviews and the result seems very positive although exact temperature varies I've never seen a test where Formula 7 wasn't the best in test. Feel free to point one out if you find one.
The Formula 7 variant is stable form -50°c all the way up to 250°C. If anyone has a PC that runs with a temperature anywhere near this please get in touch as we would like to feature it as a freak of technology.
So what's the down side? Anything this great must have a downside. Well firstly it is more expensive than silver based compounds but not by a huge amount and theres enough in the tube to do several PCs, especially if your sparing. The only notable downside I can think of is that its much thicker than silver based paste and that makes it more difficult to apply. It comes with a spreader but I don't use it. There are lots of discussions if you look around on the best way to apply it but the consensus seems to be to spread it as thinly as possible almost entirely covering the CPU top. I've tested this method as well as experimenting with my own methods. I find sparingly applying it as in the image and then evenly placing the cooler on top provides the same result as the much cited thinly spread method.
One last little issue, it's damn hard to find. We had trouble finding a wholesaler who stocks it. After finding one who does they decided to stop stocking it shortly after and we had to go on the hunt again. It would be a safe bet that you found this article while looking for suppliers of Formula 6 or Formula 7. You are in luck because its an item we always maintain stocks of, we have to we use quite a bit ourselves.