Update 3: 3 fans compared on HR-02
So I decided to test few fans at my disposal on the heatsink (HR-02 Macho rev.A). There are two NF-S12A on the bottom and rear position. When testing CPU temperatures, they run at fixed 400 RPM. There are no other moving parts in the system.
These are very subjective statements, since a certain fan can be louder, but less noticeable sound character can mask with ambient noise. I know tests are really not that scientific. Temperatures at the same RPM can be combined with subjective noise ratings, so everybody can draw their own conclusions. Scyhe Slipstream PWM
Audible at: 500-550 RPM
Sound character: typical Slipstream low pitched whooshing airflow sound, not much tonality or motor noise
CPU temperature at fixed 500 RPM: 58°CI like Slipstream fans, but I never liked how much airflow whoosh they make on low RPM. Noctua NF-S12A PWM
audible at: 650 RPM
sound character: much less airflow noise, more mid-pitched, hardly noticeable and VERY smooth sound character, even when running on higher RPM's
prime95 CPU temperature at fixed 500 RPM: 56°CNoctuas offer great improvement, both in terms of temperatures and noise, but with a big price tag. Fractal Design Silent Series R2
audible at: 550-600 RPM
sound character: small amount of ticking, not audible from more than a meter, airflow noise is somewhere in between Noctua and Scythe, hard to pinpoint, low-mid pitched
prime95 CPU temperature at fixed 500 RPM: 58°CFractal silent series really surprised me, they can stand up to Slipstream's airflow, but with better sound quality. Unfortunately they cannot be run at ultra low speeds, so I wouldn't use them as a case fans, as the airflow noise would be much more noticeable. Slipstreams are still better sounding at high RPM's.
I want my fan control to be software independent, so I decided to run 3x NF-S12A PWM (in, heatsink, out)
from one CPU fan header. PWM control can fortunately be set low enough in BIOS. Better option would be 140mm fan on heatsink, but that would block GPU.Prime95 testing under normal room temperatures:
I think cooling CPU silently won't be a problem even with high-end GPU in the system.
Next upgrade: MSI GTX 760 Twin Frozr and Corsair RM550