Yes it does make it quieter but make your mac pro run a lot hotter. With the old stock cooler the fan blow hot air outside the Computer. But with the new Accelero X2 it now blow the hot air into the Mother Board, making the Computer run hotter. If you put your hand back at the back of your Mac pro where the graphic card is you notice no air is blowing out. This is because it blowing all the hot air directly back into the Computer now. Try running intensive apps and play game for awhile and you notice your fan is working harder and your whole computer running hotter. If you don't believe me go to Newegg to read review on this product, or do some research on this.