Hot Test Results

For our power supply testing, we are using high precision electronic loads with a maximum power draw of 2700 Watts, a Rigol DS5042M 40 MHz oscilloscope, an Extech 380803 power analyzer, two high precision UNI-T UT-325 digital thermometers, an Extech HD600 SPL meter, a self-designed hotbox and various other bits and parts. For a thorough explanation of our testing methodology and more details on our equipment, please refer to our How We Test PSUs post.

The energy conversion efficiency of the Lian Li SP750 is remarkably stable, dropping an average of just 0.4% with the unit operating inside our hotbox. The degradation is greater at higher loads, naturally, but there are no signs of significant thermal stress.

The cooling fan of the Lian Li SP750 starts almost immediately after powering on the PSU into our hotbox, as expected from its thermal control circuitry. Noise levels are tolerable at first but the speed of the fan increases quickly, reaching maximum speed with a load of about 400 Watts. As the fan cannot spin any faster, the internal temperature of the units starts climbing even faster, reaching very uncomfortable temperature figures when the PSU is fully loaded in such an environment. The protective circuits did not shut down the unit and there was no indication of excessive stress to any of its performance indicators, yet we would not recommend allowing the PSU to ever run anywhere near that hot.

Cold Test Results (~25°C Ambient) Quality & Conclusion
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  • erinadreno - Monday, July 12, 2021 - link

    Is it just me or the PCB layout looks like mirrored from Corsair's SF750?
  • DanNeely - Monday, July 12, 2021 - link

    Looking at photos from the review below I don't think so. Off the bat this one has the 2 coils on the side opposite the big capacitor stacked vertically instead of side by side, the heat sinks next ot the big cap are oriented differently; and while it's hard to be sure since al of the images here were taken at more of an angle I think the Lian-Li is more densely packed.
  • romrunning - Monday, July 12, 2021 - link

    Thanks for the review! I am not surprised Lian Li entered the SFX market first, because not only do they manufacture a number of custom ITX cases (i.e. ready-made customers), but the SFX PSU market itself has fewer competitors. The ATX PSU market has enough already. Hence, it makes perfect sense to enter the SFX side first.

    The Corsair SF750 mostly dominates the SFX PSU market at the 750W point, so another competitor at that level is desirable. I'll be interested to see if this one made by Helly Technology is just as good, quality/reliability-wise, as the Corsair one.

    The fan is hopefully not a bad choice. I would have wanted one chosen more for quiet operation, because I really treasure a quiet system, especially when ITX cases don't have as much internal volume to "deaden" the sound.
  • u.of.ipod - Monday, July 12, 2021 - link

    I think it has less to do with the fan choice and more to do if they set the fan curve aggressive or not, and if they base the fan curve on actual temperature or just general load.
  • romrunning - Monday, July 12, 2021 - link

    The review said: "The 92 mm fan started when our load was just over 200 Watts", so it sounds like a more aggressive curve. I don't know if this unit has a specific "ECO-mode" or configurable semi-passive mode. I know on my SF750, I've yet to hear the fan in the PSU kick on past the initial system power-on. Personally, I'm okay with the fan running, as long as it stays quiet (or at least always less than the system/GPU fans). :)
  • Oxford Guy - Tuesday, July 13, 2021 - link

    'I think it has less to do with the fan choice and more to do if they set the fan curve aggressive or not'

    1. Ball bearing fans are noisy. Single-bearing fans are the worst.

    The only exception I have seen to this rule is some single-speed dual-bearing low-RPM fans designed for high static pressure, which did seem to be very competitive with competing tech (e.g. 800 RPM model from industrial company whose name I can't recall).

    The main reason, as far as I know, for using dual-bearing fans, is for high static pressure situations (i.e. radiators, especially those with airflow high resistance).

    2. How aggressive the fan needs to be depends on various factors that can be controlled by the OEM, such as the quality of the electronics (efficiency) and the quality of the airflow/heatsink aspect. This review suggests that one of the sinks isn't very good and gold is not the best PSU electronics can do.

    The profile isn't just plucked out of the sky. It has to provide adequate cooling under load.
  • romrunning - Monday, July 12, 2021 - link

    "What is strange here is the presence of three PCI Express connectors, because the SP750 clearly has the power output for two middle-range graphics cards but the lack of a fourth connector deprives users from that choice"

    ITX boards only have one PCIe x16 slot for a dGPU, so this isn't a problem at all.
  • Slash3 - Monday, July 12, 2021 - link

    There are a number of midsize cases that will hold a Micro ATX or full sized ATX motherboard, but still require an SFX power supply, including their own popular O11 Dynamic Mini.
  • meacupla - Monday, July 12, 2021 - link

    dGPU is dead anyways, so it doesn't matter.
  • DanNeely - Monday, July 12, 2021 - link

    Only for gaming, not compute.

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