When comparing this kit to the HD5870 stock cooler, the Thermalright Spitfire, VRM-R5 and X-Silent 140 combination managed to reduce the core temperature by a very impressive 38=B0C and 29=B0C to the VRM. These temps absolutely smashed the performance of the stock cooler, but even more impressive was how the Spitfire heatsink was more efficient than the stock cooler even while being used passively. For an after-market cooler to out perform stock is great, but to do so without the use of a fan even during the most demanding situations just puts this offering in a league of its own.