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

Protection Features and DC Power Sequencing

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: 63.8A (117.78%), 12.039V
5V: 31.1A (155.5%), 5.037V
3.3V: 30.2A (151%), 3.323V
5VSB: 4.2A (168%), 4.978V
OPP781.3W (120.2%)
OTP✓ (160°C @ 12V heat sink)
SCP12V: ✓
5V: ✓
3.3V: ✓
5VSB: ✓
-12V: ✓
PWR_OKAccurate (but less than 16ms)
Inrush: NTC thermistor & bypass relay

OCP on the +12V rail is set properly, while the minor rails have high OCP triggering points. Over-power protection is configured conservatively at 120.2%. We prefer this to an unrealistically high OPP setting.

Over-temperature protection works properly, and we confirmed that short circuit protection operates as-expected on every rail. The power-good signal is accurate, but it's far too low at ~10ms. According to the ATX specification, this should be at least 16ms.

DC Power Sequencing

According to Intel’s most recent Power Supply Design Guide (revision 1.4) the +12V and 5V voltages must be equal or greater than the 3.3V rail’s output at all times.

For our first measurement, we turn the PSU off and switch it back on without load on any of its rails. In the second test, we set the PSU to standby mode, dial in a full load, and start the PSU. In the last test, with the PSU switched off, we dial in a full load before restoring power.

Everything goes smoothly in these tests; the 3.3V rail is lower than the +12V and 5V rails at all times.

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