Pros, Cons And Final Verdict
Despite its compact dimensions, the PE-750 achieves amazing efficiency, registering among the highest levels we've seen from an 80 PLUS Platinum power supply (even the ones based on an ATX form factor). Additionally, the critical +12V rail performs well. If the 3.3V rail was just a bit better, we would be completely satisfied by the PE-750's performance. Fortunately, the 3.3V and 5V rails are only lightly used in modern systems, which is why they're considered minor. More important are the +12V and 5VSB rails, and in this PSU both perform well. The cherry on top is quiet operation up to around 500 W of load. Moreover, the semi-passive mode lasts quite a while for a high-capacity PSU with restricted dimensions and an overpopulated PCB.
The PE-750 has a number of strengths. But it also suffers some major shortcomings. A high price and short warranty are two of the most problematic. In the space where Lian Li wants to compete, two-year coverage is absurd. You also wouldn't expect to find a sleeve-bearing fan in a $160 PSU. Those fans are only suitable for entry-level power supplies, which the PE-750 is not. The expected lifetime of a sleeve bearing is much shorter than double-ball or fluid dynamic bearings. And taking into account the 85 °C bulk caps, we start to understand why Lian Li is reluctant to provide more than two years of warranty coverage. This is especially true in markets with 115 V mains, where the PSU's internal temperature will be higher due to lower efficiency.
In any case, it is a great shame to see a high-end PSU with silly weaknesses that could have easily been avoided. Both problems are easy to fix. Lian Li just needs to replace its fan and bulk caps with beefier hardware. Larger caps would facilitate a hold-up time that satisfies the ATX spec's requirement, and it wouldn't be difficult for Enhance to properly tune the power-good signal from there. Unfortunately, an inaccurate power-good signal is becoming common in high-end PSUs, and we can only hope that after heavy criticism, manufacturers stop trying to pull this nasty stunt. Power-good is there for a reason, and it has to be de-asserted before the rails drop below their corresponding levels.
With a longer warranty, a better fan, a higher temperature rating, and larger bulk caps, the PE-750 could easily earn recognition from us, despite its lofty price tag. But it seems like we'll have to wait for a revision at least before those items are addressed.
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