A power supply is the one component in a PC that runs whenever the machine is on, and it is the one where makers are least likely to publish a number. We read specification pages and datasheets for twenty two units from eleven brands, from 550W to 1300W, including three fanless models and two SFX units. Only two brands publish their own decibel figures.
Our 7 picks are listed above, with full specifications for each.
Two kinds of claim
Maker figures. be quiet! publishes a four point curve for every unit: dB(A) at 10%, 20%, 50% and 100% load. That is the most useful disclosure in any category we have covered, because it tells you what the thing sounds like at the load your machine actually sits at. SilverStone publishes single numbers, either "0 dBA" for its fanless units or "18 dBA min." for the Attis 750x.
Cybenetics grades. Everyone else who says anything publishes a letter from Cybenetics, an outside lab that measures noise across the load range and averages it. Seasonic, Corsair, ASUS, FSP and XPG all do this, and Corsair explains the method on its own pages.
The letter is more useful than it looks, because the scale is published. FSP reprints it in full beside its own grade:
- A++ is under 15 dB(A)
- A+ is 15 to under 20
- A is 20 to under 25
- A- is 25 to under 30
- Standard++ is 30 to under 35
- Standard+ is 35 to under 40
- Standard is 40 to under 45
So a graded unit tells you a band, measured by someone who is not selling it. Against a bare maker number with no distance and no load point attached, that is not a bad trade.
The name on the box is not the grade
Corsair sells the SF1000L as a "Low-Noise SFX Power Supply". Its published Cybenetics grade is Standard+, which on the scale above means at least 35 dB(A) and under 40. It is the loudest graded unit in this guide, and the only one with "low noise" in the product name.
Cooler Master's X Silent Edge Platinum 850 is another. The name promises silence and the specification table publishes neither a decibel figure nor a grade.
The lesson is dull but reliable: read the grade or the number, not the name.
Smaller can be quieter
be quiet!'s own range makes the point. The 550W Pure Power 13 M, the cheapest unit here, publishes 14 dB(A) at 100% load. The 1300W Dark Power Pro 13, the most expensive, publishes 23.2 at the same point.
That is not a fault in the big unit. A 1300W supply at full load is moving far more heat than a 550W one, and it holds 10.2 dB(A) all the way from 10% to 50% load, which is where a real machine lives. But it does mean the reflex to buy more wattage than you need does not automatically buy you quiet.
Fanless is not silent
Two makers sell fanless units here and they describe them very differently.
Seasonic's PRIME Fanless TX-700 carries a Cybenetics A++ noise grade. A unit with no fan still gets measured, because coil whine and transformer buzz are real and the lab picks them up. A++ means the average came in under 15 dB(A).
SilverStone's Nightjar NJ700 publishes "Noise Level 0 dBA" with no load point, no distance, no ambient temperature and no standard. Taken literally it says the unit emits no sound at all, which nothing does.
Both are fanless. Only one of them is telling you something that was measured.
Watch out for numbers that belong to something else
One practical warning. Corsair's power supply pages embed cross-sell blocks for its coolers, and those blocks carry their own "Noise Level" rows, such as "10 - 36 dBA". Read quickly, or scraped automatically, that number looks like it belongs to the power supply. It does not. Corsair publishes no decibel figure for any PSU in its range.
We did not measure any of these power supplies. Every figure here is the maker's own or the outside grade the maker publishes, quoted as published, with the condition attached wherever the maker attached one.
