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Protection Features, DC Power Sequencing, Cross-Load Tests and Infrared Images

Protection Features

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

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OCP (Cold @ 30°C)	12V: 99.6A (140.68%), 12.075V 5V: 32.5A (135.42%), 5.019V 3.3V: 32.5A (135.42%), 3.355V 5VSB: 6.4A (213.33%), 4.965V
OCP (Hot @ 43°C)	12V: 99.6A (140.68%), 12.083V 5V: 32.8A (136.67%), 5.022V 3.3V: 32.3A (134.58%), 3.363V 5VSB: 6.3A (210%), 4.966V
OPP (Cold @ 31°C)	1202.85W (141.51%)
OPP (Hot @ 44°C)	1203.66W (141.61%)
OTP	✓ (167°C @ 12V Heat Sink)
SCP	12V to Earth: ✓ 5V to Earth: ✓ 3.3V to Earth: ✓ 5VSB to Earth: ✓ -12V to Earth: ✓
PWR_OK	Proper operation
NLO	✓
SIP	Surge: MOV Inrush: NTC Thermistor & Bypass relay

The OCP triggering points are high on all rails, and the same goes for OPP. The PSU won't have a problem for short operation under these conditions at normal temperatures, but at high ones the platform will take lots of stress.

DC Power Sequencing

According to Intel’s most recent Power Supply Design Guide (revision 1.4), the +12V and 5V outputs must be equal to or greater than the 3.3V rail at all times. Unfortunately, Intel doesn't mention why it is so important to always keep the 3.3V rail's voltage lower than the levels of the other two outputs.

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MSI MPG A750GF — (Image credit: Tom's Hardware)

No problems here since the 3.3V rail is always lower than the other two.

Cross Load Tests

To generate the following charts, we set our loaders to auto mode through custom-made software before trying more than 25,000 possible load combinations with the +12V, 5V, and 3.3V rails. The deviations in each of the charts below are calculated by taking the nominal values of the rails (12V, 5V, and 3.3V) as point zero. The ambient temperature during testing was between 30 to 32 degrees Celsius (86 to 89.6 degrees Fahrenheit).

Load Regulation Charts

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Efficiency Graph

Ripple Graphs

The lower the power supply's ripple, the more stable the system will be and less stress will also be applied to its components.

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Infrared Images

We apply a half-load for 10 minutes with the PSU's top cover and cooling fan removed before taking photos with a modified Fluke Ti480 PRO camera able to deliver an IR resolution of 640x480 (307,200 pixels).

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The temperatures are low on all parts, despite the small heat sinks. Given these results, the fan speed profile could be more relaxed for lower noise output.

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