The noise level of each cooler was measured between 1:00 and 3:00 AM in a closed room about 20 m2 big using CENTER-321 electronic noise meter. The noise level for each cooler was tested outside the system case when the only noise sources in the lab were the cooler and its fan. The noise meter was installed on a tripod and was always at a 150 mm distance from the cooler fan rotor. The tested cooling systems were placed at the edge of the desk on a sheet of polyurethane foam. The lowest noise reading our noise meter device can register is 29.8 dBA and the subjectively comfortable noise level in these testing conditions was around 36 dBA (do not mix it up with low noise level). The fan(s) rotation speed was adjusted in the entire supported range using our precise in-house controller by changing the voltage with 0.5 V increment.
Besides the three products covered in this review, we will include noise level data of a reference NVIDIA GeForce GTX 770 and an Inno3D iChill GeForce GTX 780 HerculeZ X3 Ultra. This will help us see the difference in noise level between the two identical coolers, especially as we had certain complaints about the noisiness of the top-end Inno3D at low fan speeds. We do not do the same comparison for the two EVGA cards we’ve tested since they are identical in noisiness.
The vertical dotted lines mark the top speed of the coolers' fans in the automatic regulation mode. The results are presented in the following diagram and table:
Comparing the two cards from Inno3D, we can see that the HerculeZ X3 Ultra is quieter on the GeForce GTX 770. So there is a difference in the quality of the fans, which isn’t good for the top-end products. In the automatic regulation mode the Inno3D iChill GeForce GTX 770 HerculeZ X3 Ultra turns out to be the quietest in this review, being much better than its opponents. As for the other original GeForce GTX 770s, the MSI is slightly quieter than the EVGA. Still, the EVGA GeForce GTX 770 Superclocked ACX is not as noisy as the reference GeForce GTX 770 from Nvidia which, in its turn, is regarded by many reviewers as acoustically comfortable.