These are summary graphs. The sound measurements were made 10cm to the side of the center fan. This was done to capture the differences between center fans as well as to compare the SPL's when there was no fan in the middle (look at all the chapters of item 4 in my sig; it was a long run).
The noise the push fans make is much more variable. And yes, the difference between an AP-30 and an R4 is significant. Look to item 1 in my sig to get a handle on that.
As for fan speeds, there is often great variability. Sellers typically promise plus or minus fifteen percent of the rated rpm.
Okay. Thanks for your reply. I know that between AP 30 et R4 there isa big difference, but AP15 should be in the same range?
if you had to choose between the R4 and the XSPC 120mm 1650rpm, which one you would take for heatsink, and for case fan?