The Server Fan 4028 and 4056, both rated at 30000RPM, are compact cooling solutions for servers, but their design differences translate to distinct performance trade-offs, making them suitable for varied use cases.

First, form factor sets them apart: the 4028 follows a 40mm (width) x 28mm (depth) profile, while the 4056 is deeper at 40mm x 56mm. This dimensional gap directly impacts airflow and static pressure: the 4056, with its larger blade surface area and deeper housing, delivers 18–25 CFM of airflow and 80–120 Pa of static pressure, compared to the 4028’s 12–18 CFM and 60–90 Pa. For servers with dense component layouts (e.g., multi-GPU rendering servers or high-density storage arrays), the 4056’s superior pressure ensures airflow penetrates tight gaps between heat sinks, preventing hotspots. The 4028, however, excels in ultra-compact chassis (e.g., 1U or 2U servers with minimal internal clearance) where the 4056’s depth would cause fitment issues.

Power consumption and efficiency also differ: the 4056 typically draws 0.8–1.2A at 12V, while the 4028 uses 0.6–0.9A, making the latter more energy-efficient for low-to-moderate heat loads. Noise is another consideration: at 30000RPM, the 4028 generates 50–60 dB, slightly less than the 4056’s 55–65 dB, thanks to its smaller, lighter blades—this is advantageous for edge computing servers deployed in office or retail environments where noise is a concern.

Reliability features are similar (BLDC motors, PWM control, and dual-ball bearings), but the 4056’s deeper housing provides better heat dissipation for the motor itself, extending its MTBF to 60,000 hours (vs. 50,000 hours for the 4028). Ultimately, the 4056 is a “high-performance workhorse” for extreme heat scenarios, while the 4028 is a “space-saving efficiency option” for constrained, moderate-heat environments.