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.

Cold Test Results (~25°C Ambient) Power Supply Quality & Conclusion
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  • Oxford Guy - Friday, September 16, 2022 - link

    Small form factors and high wattage are generally mutually exclusive, unless you have impaired hearing and no tinnitus.

    'The use of a low-profile 92 mm fan inside such a compact unit with significant thermal losses did have the expected side effect of high audible sound pressure levels.

    Once the fan starts, it quickly becomes clearly audible, with the noise staying within relatively comfortable boundaries up to about 500 Watts.'

    So, maybe these companies should start calling these units 500W models rather than 850.
  • meacupla - Sunday, September 18, 2022 - link

    The only reason to get an 850W for SFX PSUs, is so that the PC won't crash when an RTX 3080Ti, or something as power hungry, causes a massive transient spike.
    You could probably get away with a 750W ATX PSU, but SFX PSUs are known for not handling transient spikes as well as ATX.
  • Harry_Wild - Monday, September 26, 2022 - link

    Looking for a rectangle shape for my Lenovo Workstation SFF desktop! 850W would be great! $170.00 …sold!
  • shamaizas - Saturday, October 15, 2022 - link

  • shamaizas - Saturday, October 15, 2022 - link

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