Seasonic G Series V2 550 W Review 16

Seasonic G Series V2 550 W Review

Efficiency, Temperatures & Noise »

Test Setup

All measurements were performed using two Chroma 6314A mainframes equipped with the following electronic loads: six 63123A [350 W each], one 63102A [100 W x2], and one 63101A [200 W]. The aforementioned equipment is able to deliver 2500 W of load, and all loads are controlled by a custom-made software. We also used a Rigol DS2072A oscilloscope kindly sponsored by Batronix, a Picoscope 3424 oscilloscope, a Picotech TC-08 thermocouple data logger, two Fluke multimeters (models 289 and 175), and a Yokogawa WT210 power meter. We also included a wooden box, which, along with some heating elements, was used as a hot box. Finally, we had at our disposal three more oscilloscopes (Rigol VS5042, Stingray DS1M12, and a second Picoscope 3424), and a Class 1 Bruel & kjaer 2250-L G4 Sound Analyzer which is equipped with a type 4189 microphone that features a 16.6 - 140 dBA-weighted dynamic range. You will find more details about our equipment and the review methodology we follow in this article. We also conduct all of our tests at 40°C-45°C ambient to simulate the environment seen inside a typical system with a higher accuracy, with 40°C-45°C being derived from a standard ambient assumption of 23°C and 17°C-22°C being added for the typical temperature rise within a system.

Rigol DS2072A kindly provided by:

Primary Rails Voltage Regulation

The following charts show the voltage values of the main rails, recorded over a range from 60 W to the maximum specified load, and the deviation (in percent) for the same load range.

5VSB Regulation

The following chart shows how the 5VSB rail deals with the load we throw at it.

Hold-up Time

Hold-up time is a very important PSU characteristic and represents the amount of time, usually measured in milliseconds, a PSU can maintain output regulations as defined by the ATX spec without input power. In other words, it is the amount of time the system can continue to run without shutting down or rebooting during a power interruption. The ATX specification sets the minimum hold-up time to 16 ms with the maximum continuous output load. In the following screenshot, the blue line is the mains signal and the yellow line is the "Power Good" signal. The latter is de-asserted to a low state when any of the +12V, 5V, or 3.3V output voltages fall below the undervoltage threshold, or after the mains power has been removed for a sufficiently long time to guarantee that the PSU cannot operate anymore.

Even though it uses a smaller bulk cap, the unit achieves a higher hold-up time than its predecessor. Seasonic informed us that they made a couple changes which increased the hold-up time despite the use of a smaller cap in the APFC.

Inrush Current

Inrush current or switch-on surge refers to the maximum, instantaneous input-current drawn by an electrical device when it is first turned on. Because of the charging current of the APFC capacitor(s), PSUs produce large inrush-current right as they are turned on. Large inrush current can cause the tripping of circuit breakers and fuses and may also damage switches, relays, and bridge rectifiers; as a result, the lower a PSU's inrush current right as it is turned on, the better.

Inrush current was a little lower than with the previous generation G-550 because of the smaller bulk cap.

Voltage Regulation and Efficiency Measurements

The first set of tests revealed the stability of the voltage rails and the efficiency of the G-550. The applied load was approximately equal to 10%-110 % of the maximum load the PSU can handle, in 10% increments.

We conducted two additional tests. In the first test, we stressed the two minor rails (5V and 3.3V) with a high load while the load at +12V was only 0.10 A. This test reveals whether the PSU is Haswell ready or not. In the second test, we dialed the highest load the +12V rail can handle while the load on the minor rails was minimal.

Voltage Regulation & Efficiency Testing Data - Seasonic SSR-550RM V2
Test12 V5 V3.3 V5VSBPower
EfficiencyFan SpeedFan NoiseTemp
10% Load2.704A1.955A1.955A0.995A54.71W82.28%755 RPM30.3 dBA 36.89°C0.882
12.260V5.103V3.372V5.019V66.49W 38.71°C230.2V
20% Load6.446A2.936A2.941A1.195A109.74W88.24%755 RPM30.3 dBA 37.43°C0.955
12.241V5.094V3.363V5.008V124.36W 39.45°C230.2V
30% Load10.530A3.434A3.452A1.401A164.79W90.21%790 RPM31.7 dBA 38.09°C0.979
12.225V5.088V3.356V4.996V182.68W 40.28°C230.2V
40% Load14.630A3.931A3.938A1.601A219.75W90.88%1430 RPM43.3 dBA 40.03°C0.987
12.208V5.081V3.351V4.985V241.80W 41.52°C230.2V
50% Load18.397A4.925A4.935A1.806A274.71W90.82%2120 RPM47.3 dBA 41.68°C0.992
12.190V5.073V3.341V4.973V302.49W 43.55°C230.2V
60% Load22.176A5.919A5.935A2.015A329.69W90.67%2190 RPM48.1 dBA 41.83°C0.995
12.172V5.064V3.334V4.962V363.62W 44.04°C230.2V
70% Load25.966A6.921A6.944A2.220A384.68W90.46%2200 RPM48.2 dBA 43.14°C0.995
80% Load29.763A7.917A7.959A2.429A439.56W90.16%2200 RPM48.2 dBA 43.60°C0.996
12.136V5.049V3.316V4.937V487.54W 46.59°C230.1V
90% Load33.998A8.432A8.492A2.431A494.63W89.90%2215 RPM48.4 dBA 44.71°C0.996
12.119V5.042V3.310V4.931V550.21W 48.08°C230.1V
100% Load38.200A8.935A8.997A2.539A549.47W89.43%2215 RPM48.4 dBA 45.34°C0.997
12.102V5.034V3.301V4.920V614.40W 48.99°C230.1V
110% Load42.813A8.948A9.012A2.542A604.44W88.89%2215 RPM48.4 dBA 45.93°C0.997
12.082V5.028V3.295V4.913V680.00W 50.10°C230.1V
Crossload 10.099A12.005A12.005A0.003A102.08W83.50%2190 RPM48.1 dBA 43.90°C0.952
12.247V5.068V3.333V5.025V122.25W 46.95°C230.3V
Crossload 244.978A1.002A1.003A1.002A557.59W90.10%2215 RPM48.4 dBA 45.22°C0.997
12.099V5.060V3.331V4.975V618.85W 49.15°C230.1V
Voltage regulation on all rails was tight, but not as tight as with the previous model. The changes Seasonic made to allow for higher efficiency at lower loads and increased hold-up time probably had some effect on voltage regulation, although the latter is still very good. The G-550 also had absolutely no problem delivering its full power at very high ambient temperatures, but the fan did rotate at full speed under those conditions, which produced a lot of noise. The fan profile is very aggressive above 40°C, and we think Seasonic should use a more relaxed profile. The unit's efficiency restricts energy losses nicely, so the fan doesn't have to handle high thermal loads. Speaking of the unit's efficiency, it is quite high, although we would like to see a slightly higher reading at 20% load.
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