Quote Originally Posted by Sherif846 View Post
To Martin and the other folks,

Thanks Martin for the excellent work and efforts. I just could not find in the stickies or in this thread anything about the difference between using 120X25 and 120X 38 on radiators. As I am about to build my system, and thanks to your charts I narrowed down my choice, but I don't know which to use, 25mm or 38mm fans?and what effect would each have on the flow? I am probably going for a Feser monsta, to cool 2 blocks ( cpu+gpu) and another seperate loop for nb, sb and other chips.
If I'm not mistaken, you need a 38mm on a radiator. In general a 25 vs 38 should be about the same in terms of CFM vs dB in open air, but when you have obstructions like in a radiator, Martin showed that the 38mm fans really shine. Vapor did a test in open air and you can see that the 25mm fans do quite well there. Sure he didn't use as many 38mm fans so it's a little hard to tell, but looking at Martin's graph you can see that the 38mm fans stand out to the upper left in those CFM vs dB graphs.