DC Load Regulation and AC Ripple
Testing Methodology
Establishing an accurate load is critical to testing and evaluating a PC power supply. PCPerspective’s power supply test bench can place a precise DC load on the PSU under test. Each power supply is tested under controlled, demanding conditions up to its maximum rated load (at 40ºC). Our current suite of tests includes:
• DC Load Regulation
• AC Ripple and Noise
• Efficiency
• Differential Temperature
• Noise
The Seasonic PRIME 600W Titanium Fanless power supply was evaluated on both features and performance. A full range of equipment was used to test the power supply under controlled load conditions.
• (2) CSI3710A Programmable DC load (+3.3V and +5V outputs)
• (4) CSI3711A Programmable DC load (+12V)
• (2) 200W Precision resistor load bank (+12V)
• Switchable precision resistor load bank (-12V and +5VSB)
• Agilent 34401A digital multimeter (Accuracy ±0.0035% vDC)
• Extech 380803 Power Analyzer (Accuracy ±0.5% of full scale)
• DS1M12 "StingRay" digital oscilloscope (20M S/s with 12 Bit ADC)
• Powerstat Variable Autotransformer, 1.4 KVA, 0-140 VAC
• Extech Model 407738 digital sound level meter (Accuracy ±1.5 dB)
The following cables/connectors were used to connect the power supply to the PCPerspective power supply test equipment.
• (1) 20+4 pin ATX
• (2) 8-pin EPS/ATX12V
• (4) 6-pin PCI-E
• (3) SATA
• (2) Molex
DC Output Load Regulation
To simulate demanding and maximum loading conditions, the PRIME 600W Titanium Fanless power supply was connected to the load testers and supplied with 120 VAC. In this test we are interested in seeing how well a PSU can maintain the various output voltages while operating under different loads.
The ATX12V V2.2 tolerance for voltages states how much each output (rail) is allowed to fluctuate and has tighter tolerances now for the +12V outputs. I have also included a second table of expanded tolerances (±1% to ±6%) for reference.
The following tables list the DC voltage results for the 600W Fanless PSU while operating on 120 VAC, 60 Hz.
The power supply produced outstanding voltage regulation on all of the DC outputs with all rails staying within ±1% of the recommended guidelines.
AC Ripple and Noise on the DC Outputs
The amount of AC ripple and noise present on the DC outputs was checked using a digital oscilloscope. This AC component may be present in the KHz range where most switching power supplies operate or it may be more prevalent at the 60 Hz line frequency. We adjust the O-scope time base to look for AC ripple at both low and high frequencies. The ATX12V V2.2 specification for DC output noise/ripple is defined in the ATX12V Power Supply Design Guide.
Ideally we would like to see no AC ripple (repetitive) or noise (random) on the DC outputs – the cleaner the better! But in reality there will always be some present. I measured the amplitude of the AC signal (in millivolts, peak-to-peak) to see how well the power supply complied with the ATX standard. The following table lists the ripple/noise results during all of the load tests for the main output voltages of interest.
The Seasonic PRIME 600W Titanium Fanless power supply did an excellent job of keeping the AC ripple and noise well under control.
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In what world is this
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In what world is this F*****G power supply going to stay below 40degC to keep from dropping down to 480W?
It will also dissipate much MORE HEAT into the main case anyway thus the other parts will have fans spin up more so it may be louder anyway.
I doubt you’d make a completely FANLESS system either (I know they recommend against that) since if you needed that much power and had no fans I doubt you’d keep the temperature below 40degC (especially in warmer areas).
Maybe I’m just stupid, but can anyone explain who might use this besides someone with relatively LOW POWER draw who wants a really quiet system (for which their already are PSU’s that turn OFF their fans anyway)?
At over 91% efficiency, only
At over 91% efficiency, only 9% of electricity is converted into heat, which in the case of this power supply, is 54 watts at 100% load. It’s negligible.
I use a Fanless SeaSonic SS-520FL2 in my system paired with an overclocked 1080 Ti. It’s a flawless operation. The system is liquid cooled with fans set to barely audible levels, so even under load, you can’t hear anything.
Your math is backwards,
Your math is backwards, although your error in this case is rather insignificant.
The 91% are what the power supply delivers. 100% is what it draws from mains. In a simplified scenario, if the PSU delivers 600 W with a 91% efficiency, then it draws around 659 W from the mains (659 * 91% = 600). Thus, the loss is not 54 W but 59 W.
To add to your point for
To add to your point for his/her benefit:
A simple shorthand for figuring out this sort of problem is to take the power out and not do any sort of multiply but rather perform a divide. Power out divided by efficiency equals power in. Power in minus power out equals power lost in conversion.
600 watts out / 0.91 efficient = 659 watts in
659 watts in – 600 watts out = 59 watts lost in conversion
You can always mount the PSU
You can always mount the PSU _outside_ the case (if the case allows of course)
Done it once at a system with dual Nocona Xeon’s.. That was the only option to lower overall fan noise..
Unfortunately back then the max fanless PSU you could find was topping at 300W..
Blower style GPU is probably
Blower style GPU is probably what this is intended for.
80+ Silver is a rating which
80+ Silver is a rating which no one seem to aim for anymore. You can find numerous power supplies rated for everything under the sun but not 80+ Silver. I wonder why that is.
Well many Dells, HPs and
Well many Dells, HPs and other PCs are usually been with 80plus silver PSU(With OEMs like Lite ONs, FSPs, Deltas). But now-a-days those too have been moving to gold rated ones…
I actually don’t remember seeing silver rated psus on normal retail sale.
Sort of agree, any power
Sort of agree, any power supply of this size should come with a fan. You decide to run it at the speed, sound of your desire. Heat rises.
Couple of fan headers would
Couple of fan headers would be nice.
40degC vs 9% heat
40degC vs 9% heat dissipation.
First off, HEAT and TEMPERATURE are certainly related but it’s the DENSITY of heat that matters most, especially if a temperature sensor is near components in the PSU that get hotter than the average temperature of that PSU.
Remember that the INTERNAL case temperature can get pretty high, though of course it’s much lower at the bottom. However, I have a sensor at the BOTTOM of my motherboard hitting roughly 50degC when gaming (i7 + GTX1080, 3xNoctua case fans at 700RPM).
So how hot is this PSU getting in a typical case at say 500W PSU load? (the spikes you should care about)
So adding 50W or so of heat raises the temperature above whatever it would normally be just sitting at that point in the case. If you’re at 35degC then maybe that’s enough to hit 40degC.
*As a solid product it may make sense as a long-term investment, but I’d like more numbers on how close to the 40degC cut-off it’s getting to based on (at 500W+ power draw):
a) ambient room temperature, and
b) case cooling
In the SUMMER if I hit 30degC for example would I drop down to 480W power load in a particular system?