TweakTown uses a different method for testing CPU heatsinks which allows for an even playing field across all product tests. We feel that by using the same ambient temperature and strict lab-like testing procedures we are able to accurately compare one product to another. More information on our testing procedure can be found in the T.E.C.C. article here.
Going in, I was a little worried about the price of the HDT-SD964. Would the cooler end up being a dud or would it shine? - The results show that my concerns were justified. But there is some things to consider. First; all of the HDT coolers we have tested so far have been 120mm models and our XIGMATEK sample uses a 92mm fan. While the results show the cooler performs a little worse than the 120mm models, the difference is right around 3-4 degrees Celsius. Given the larger surface area and additional CFM of the larger coolers, I would bet a 120mm variant would compete with our other coolers.
92mm fans generally run a little louder than 120mm fans, just as 80mm fans are compared to 92mm. This is because the fan blades need to spin at a faster speed to move the same amount of air than their larger counterparts. The 92mm used with the HDT-SD964 puts the cooler at a disadvantage in the noise category when compared to some of the others, but it is a trade-off you make when trying to stuff an enthusiast class cooler into a smaller enclosure.