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Load Regulation, Hold-Up Time & Inrush Current

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

Corsair CX650M

FSP Hydro G 650

Corsair RM550x

Primary Rails And 5VSB Load Regulation

Load Regulation testing is detailed here.

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Hold-Up Time

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

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The hold-up time we measure is long, and the power-good signal is accurate. We do find a problem during those tests though: the power-good signal's ripple is too high, and we also notice some oscillations on the +12V rail.

Inrush Current

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

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The inrush current is crazy-high with both voltage inputs.

Load Regulation And Efficiency Measurements

The first set of tests reveals the stability of the voltage rails and the Caslon II’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.

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Test #	12V	5V	3.3V	5VSB	DC/AC (Watts)	Efficiency	Fan Speed	PSU Noise	Temps (In/Out)	PF/AC Volts
1	3.168A	1.947A	1.956A	0.982A	59.856	79.956%	1014 RPM	29.0 dB(A)	38.18°C	0.974
12.080V	5.131V	3.373V	5.090V	74.861	43.86°C	115.18V
2	7.342A	2.925A	2.939A	1.182A	119.586	84.749%	1097 RPM	30.8 dB(A)	38.77°C	0.970
12.080V	5.127V	3.368V	5.075V	141.106	44.75°C	115.20V
3	11.911A	3.414A	3.418A	1.385A	179.512	86.140%	1191 RPM	32.8 dB(A)	39.27°C	0.985
12.049V	5.126V	3.363V	5.055V	208.395	45.63°C	115.11V
4	16.500A	3.903A	3.929A	1.589A	239.524	86.532%	1277 RPM	34.6 dB(A)	39.81°C	0.992
12.020V	5.123V	3.358V	5.038V	276.804	46.59°C	115.03V
5	20.756A	4.894A	4.920A	1.794A	299.638	86.360%	1303 RPM	34.9 dB(A)	40.12°C	0.995
12.004V	5.106V	3.352V	5.018V	346.962	47.22°C	115.04V
6	25.012A	5.884A	5.916A	2.002A	359.764	85.891%	1440 RPM	37.1 dB(A)	41.32°C	0.996
11.993V	5.098V	3.346V	4.997V	418.860	49.08°C	114.95V
7	29.262A	6.885A	6.913A	2.211A	419.480	85.225%	1498 RPM	38.3 dB(A)	41.88°C	0.997
11.974V	5.083V	3.341V	4.977V	492.203	50.21°C	114.86V
8	33.559A	7.885A	7.916A	2.422A	480.036	84.370%	1565 RPM	38.8 dB(A)	42.10°C	0.997
11.968V	5.073V	3.335V	4.955V	568.962	51.86°C	114.76V
9	38.300A	8.378A	8.411A	2.429A	539.358	83.288%	1630 RPM	39.7 dB(A)	44.17°C	0.997
11.928V	5.074V	3.329V	4.942V	647.581	54.90°C	114.75V
10	43.142A	8.876A	8.937A	2.539A	600.082	82.220%	1620 RPM	39.6 dB(A)	45.90°C	0.997
11.888V	5.071V	3.323V	4.924V	729.847	56.93°C	114.65V
11	48.352A	8.865A	8.947A	2.542A	660.081	81.123%	1615 RPM	39.5 dB(A)	46.79°C	0.997
11.848V	5.077V	3.319V	4.919V	813.676	58.24°C	114.55V
CL1	0.136A	14.004A	13.999A	0.000A	113.853	75.836%	1580 RPM	39.0 dB(A)	43.47°C	0.977
12.888V	4.650V	3.356V	5.137V	150.130	52.67°C	115.18V
CL2	44.997A	1.002A	1.000A	1.000A	537.095	83.643%	1590 RPM	39.1 dB(A)	45.83°C	0.997
11.633V	5.255V	3.336V	5.043V	642.129	56.69°C	114.76V

Load regulation on the +12V rail is mediocre. Moreover, the Caslon II 600W's performance in our cross-load tests is bad, as expected, due to the secondary side's group regulation scheme.

Although the efficiency levels we measure are low, they satisfy the 80 PLUS Bronze requirements even under high operating temperatures. The fan profile does get aggressive, though. There is a slight reduction in fan speed during our full load and overload tests simply because that circuit is driven by the +12V rail, which drops notably during those tests.

The low-speed fan doesn't go above 40 dB(A). But even during our first test its noise output is close to 30 dB(A), so we can't exactly call it quiet, either.

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

6 Comments Comment from the forums

nobspls

Why would anyone choose this one say over the Corsair CX650M? Which you can get typically for $50.
Reply
Aris_Mp

Personally I would also take the CX650M in any day of the week, for $50.
Reply
spentshells

" Not only does this minimize your carbon footprint"

The idea of conserving electricity is a fallacy, if you use less the people selling can sell more to someone else..... they aren't just holding on to the energy you saved because you're a hero saving the world.

Making your footprint smaller doesn't matter in the least when someone else's foot print just gets that much bigger.

Save some money, sure but for how long? The less you use the more they can charge for that smaller amount later on..... that's how it is.

On a different note, Ill likely try the psu out at one point on a build for someone else.
Reply
rohs42

> The idea of conserving electricity is a fallacy

No it isn't. Of course a 100 megawatt generator will not be turned off if someone saves 10 watts of power. But if a 10 million people save 10 watts of power, then of course it will be turned off. And if 100 million people save 10 watts, then there'll be no business case for that new gigawatt power plant.

As citizens, consumers and voters we all bear a small share of responsibility for the state of the world, and we all have a small part to play in making it better. It's only through working together that humanity improves. Your appeal to helplessness and apathy is pathetic.
Reply
jabliese

Hey Tom's,

Once upon a time, we had an extensive brown out at work, which went on for 3 days. On day 2, I was surprised to find many of the PC's that were still working were on 60v power. Over the years, it did not seem to have a adverse affect on any of the power supplies. Lately, I have been wondering what their efficiency numbers looked like during that time, any chance you could add a severe undervolt test to the power supply suite?
Reply
Aris_Mp

60V is too low. Most PSUs won't even work at such low voltage. I am surprised to hear that the PSUs at your work were working under such conditions for days.

Efficiency drops along with voltage input. I want to add more protection tests, however I already have enough fails with the current ones. Nonetheless, I am keeping every suggestion under consideration.
Reply

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