The BitFenix Whisper M 450W & 850W PSU Review

Hot Box Test Results

This new platform probably delivers the best power quality that we have previously seen from any Channel-Well Technology design. The ripple suppression of the 450W unit is amazing, with the 12V line registering a maximum of 20 mV and the 3.3V/5V barely reading a voltage ripple of 12 mV. 

We can see that the 850W version delivers similar performance under the same loading conditions, with the voltage ripple readings increasing only at loads far beyond the capacity of its smallest sibling. Still, the 32 mV voltage ripple on the 12V line is an outstanding figure under a load of 850 Watts. The voltage regulation is nearly identical for every line of both units, with an average of just 1%.

The higher ambient temperatures in our hotbox testing had almost no impact on the energy conversion efficiency of the Whisper M 450W PSU at all, with the unit technically maintaining 80Plus Gold efficiency levels even under such conditions. Respectively, the efficiency of the Whisper M 850W PSU dropped by an average of just 0.5%. The drop is a little greater than that of the 450W model, but minimal nonetheless. These figures suggest that the components are of excellent quality and adequately oversized, allowing the Whisper M PSUs to seamlessly operate under the most adverse of system conditions.

Considering the small heatsinks and especially because the 850W version is using the exact same heatsinks as the 450W version, we expected to see higher operating temperatures during our testing. However, it seems that BitFenix went with a simple, yet effective way of fan speed control that completely ignores the load and adjusts the fans only according to their internal temperature.

As a result, the Whisper M units cannot really operate quietly in a very hot environment, but the internal temperatures will always remain at perfectly safe levels.