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Seasonic Prime 850 W Titanium PSU Review

Seasonic made an impressive entry in the 80 PLUS Titanium category with its Prime series. This line's current flagship, offering 850W capacity, is being reviewed today. Besides high efficiency, it sports quiet operation and top performance.

Protection Features

Check out our PSUs 101 article to learn more about PSU protection features.  

Our protection features evaluation methodology is described in detail here.

Protection Features
OCP12V: - 5V: 28.1A (140.5%) 3.3V: 27.3A (136.5%) 5VSB: 4.1A (136.7%), 79.86mV Ripple
OPP1178.81W (138.7%)
OTPYes (>130°C secondary heat sink)
SCP12V: Yes 5V: Yes 3.3V: Yes 5VSB: Yes -12V: Yes
PWR_OKProper operation
SIPSurge: MOV Inrush: NTC thermistor & bypass relay

OCP's triggering points are quite high on the minor rails, though this won't create any trouble since load regulation and ripple suppression are kept under control. However, at 5VSB, ripple with 4.1A is higher than the specification allows, while with only 0.1A lower load it's normal again. Seasonic should look into this and fix it. Lastly, the OPP is set really high. Then again, the PSU doesn't have any problems under almost 1.2kW of load (at normal ambient temperatures, at least).

The other protection features operate properly. OTP is notably present and configured at an optimal level, allowing the PSU to run even under 50°C temperatures per the ATX specification's recommendation.

Aris Mpitziopoulos
Aris Mpitziopoulos is a Contributing Editor at Tom's Hardware US, covering PSUs.