When I was asked to review this new thermal compound and TIM cleaner from Phobya, my first thought was that this is an ideal opportunity for me to test a few compounds and see which suits my needs best. I then decided I wanted to be thorough, rather than quick. Then the power supply on my test rig exploded! Not one to be put off, I purchased a replacement (my spare is not powerful enough for my test system) and got down to testing. My test rig consists of a Rampage IV Extreme X79 motherboard with an i7-3930K, and an EVGA GTX 570 Superclocked, both watercooled. The processor is cooled by a Swiftech Apogee HD waterblock, cooled by chilled water set at 11 degrees. As a lot of TIM needs to be heated in order to spread thinly betwen the CPU and cooler, I set out with the twin goals of seeing how efficient this compound is under cool temperatures, as well as seeing how it commpares to a variety of other compounds. The thermal compounds I tested (the viscosity varied from almost liquid to a thick paste) are: Phobya HeGrease Extreme Thermaltake TG1 Arctic MX2 IC Diamond Antec Formula 7 For each compound, I ran the Folding@Home client for 12 hours to set the compound. I then let the system idle in Windows 7 for 30 minutes before measuring the temperature of the hottest processor core with the water temperature at 11C. I then ran Prime95 for 30 minutes, and measured the temperature of the hottest core with the water temperature again at 11C. To apply each compound, I applied a small amount, about the size of a grain of rice, in the centre of the processor. The compounds all spread by roughly the same amount over the duration of each test, except the MX2, which is much less viscous than the others and also has a lower thermal conductivity rating. It was evident from the way they spread that the IHS is very slightly rounded, so none of the compounds spread evenly. Looking first at idle temps, Phobya HeGrease Extreme had a delta T of 7 degrees. Thermaltake TG1 recorded 7.4C, Arctic MX2 was 7.1C, IC Diamond 7.2C and Antec Formula 7 gave a delta T of 7.6C. As expected, every sample I tested gave idle temps within less than one degree of each other. When fully loaded on all cores, the range of temperatures was a little wider. Looking at them in the same order, Phobya HeGrease gave a delat T of 24.5C. Thermaltake TG1 gave 25.4C, Arctic MX2 recorded 24.7C, IC diamond 25.8C and Antec Forumla 7 26.9C. Using the supplied TIM clean, I was able to wipe even the most stubborn and sticky compounds easily from both the CPU and the waterblock. I have ben using another brand of TIM clean for 6 years, and that always leaves a thin greasy film. Phobya TIM clean does not leave as much residue, and what it does leave wipes off very easily with a dry cloth. The results are a little surprising, as Arctic MX2 has the lowest thermal conductivity rating of all the samples tested, yet when idling and under load it performed beter than all but the Phobya compound, which performed best out of the selection. I wonder if some of that is due to the more viscous compounds needing heat in order to set properly. I retested the HeGrease using the supplied spatula, but found it is too viscous to spread easily, making the supplied spatula redundant. I have always believed it best to apply a small amount and allow the cooler to spread it, and for me this is confirmed by the observed results. I also noted that, at £6.34 for a 3.5 gram syringe, Phobya HeGrease is the cheapest of the tested compounds, 2 of which are no longer available where I purchased them. So as well as being the top performer it is the best value for money.