FSP Hydro PTM 650W PSU Review: Clean, Quiet Power for Mid-Range PCs

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Load Regulation, Hold-Up Time and Inrush Current

To learn more about our PSU tests and methodology, please check out How We Test Power Supply Units. 

Primary Rails And 5VSB Load Regulation

Load Regulation testing is detailed here.

Hold-Up Time

Our hold-up time tests are described in detail here.

The hold-up time we measured falls short of 17ms. We expected this to be the case, give the bulk capacitors' low capacity.

Inrush Current

For details on our inrush current testing, please click here.

The inrush current with 115V input is normal. It's too high with 230V input, though.

Load Regulation And Efficiency Measurements

The first set of tests reveals the stability of the voltage rails and the HPT650M’s efficiency. The applied load equals (approximately) 10 to 110 percent of the PSU's maximum load in increments of 10 percentage points.

We conducted two additional tests. During the first, we stressed the two minor rails (5V and 3.3V) with a high load, while the load at +12V was only 0.1A. This test reveals whether a PSU is compatible with Intel's C6/C7 sleep states or not. In the second test, we determined the maximum load the +12V rail could handle with minimal load on the minor rails.

Swipe to scroll horizontally
Test #12V5V3.3V5VSBDC/AC (Watts)EfficiencyFan SpeedPSU NoiseTemps (In/Out)PF/AC Volts
13.563A1.963A1.960A0.986A64.78486.016%708 RPM17.1 dB(A)40.10°C0.818
28.124A2.951A2.948A1.183A129.28889.963%708 RPM17.1 dB(A)40.63°C0.931
313.089A3.450A3.433A1.385A194.38391.334%705 RPM17.0 dB(A)41.25°C0.963
418.063A3.949A3.952A1.588A259.61891.690%705 RPM17.0 dB(A)41.52°C0.976
522.715A4.947A4.955A1.792A324.90491.537%705 RPM17.0 dB(A)42.15°C0.982
627.312A5.949A5.963A1.998A389.43991.085%723 RPM17.9 dB(A)42.67°C0.986
731.986A6.955A6.976A2.206A454.76890.384%945 RPM26.2 dB(A)43.18°C0.987
836.666A7.963A7.996A2.414A520.08389.698%1143 RPM31.5 dB(A)43.84°C0.988
941.746A8.476A8.505A2.418A585.01789.008%1300 RPM35.2 dB(A)44.39°C0.989
1046.774A8.990A9.045A2.524A649.76288.218%1472 RPM38.2 dB(A)45.53°C0.989
1152.200A9.000A9.064A2.526A714.60487.365%1653 RPM41.1 dB(A)46.59°C0.989
CL10.143A14.003A14.001A0.000A119.27786.023%815 RPM21.2 dB(A)42.12°C0.931
CL254.179A1.002A1.002A1.000A665.50388.532%1462 RPM37.9 dB(A)45.32°C0.989

Load regulation on the +12V rail is satisfactory, since it lands within 1%. However, the HPT650M still can't compete against other high-end, similar-capacity PSUs in this discipline. The minor rails (especially 3.3V) aren't as tight. The same goes for the 5VSB rail, though at least it falls within spec.

The fan spins at very low speeds, even under tough conditions. We have to push the PSU beyond its limits for the fan to exceed 40 dB(A).

At the same time, none of the efficiency levels we measured satisfy the 80 PLUS Platinum standard's requirements. Then again, we test at high ambient temperatures, causing efficiency to take a hit. The 80 PLUS organization performs its certifications at 23°C (±5°C), which is an unrealistic temperature to expect inside of a chassis.

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Contributing Editor

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