The FSP Dagger Pro SFX 850W PSU Review: Awesome Power in a Small Shell

Hot Test Results (~45°C Ambient)

Despite its small proportions and significant thermal losses, the energy conversion efficiency of the FSP Dagger Pro 850W PSU does not degrade significantly across most of the load range when it operates in a high-temperature environment. The average efficiency reduction is less than 1.1%. However, there is a very significant degradation when the load is greater than 750 Watts which reaches up to 3.6% at maximum capacity, suggesting high thermal stress.

Despite the high ambient temperature, the 92 mm cooling fan started only a little bit sooner while the Dagger Pro was operating inside our hotbox. Noise levels initially are low but the speed of the fan climbs up quickly as the load increases, reaching clearly audible figures when the load is less than 300 Watts. Ultimately, the fan reaches and maintains its maximum speed, producing noise that would trouble even the most tolerant of users.

The small proportions and significant thermal losses of the Dagger Pro, combined with the low-profile 92 mm fan, result in very high internal temperatures when the ambient temperature is very high. Once the load is greater than 600 Watts, the fan and the heatsinks seem no longer able to cope with the thermal load and the temperature begins rising sharply and well over 100 °C. We also failed to trigger an over temperature protection (OTP) shutdown, meaning that FSP’s engineers probably have the limit set exceedingly high.