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Quietest low profile CPU cooler: Noctua's 65 mm NH-L9x65 lists 14.8 dB(A) on its adaptor

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Quietest low profile CPU cooler

Noctua's NH-L9x65 prints the lowest figure in its maker's low profile range: 14.8 dB(A) at 1800 RPM with the included Low-Noise Adaptor, at 65 mm tall. The 70 mm NH-L12S follows at 16.8 on its adaptor.

Bare, every 92 mm Noctua lists 23.6 dB(A), the 37 mm NH-L9a-AM5 and NH-L9i-17xx included.

Thermalright's figures are for fans, 22.4 dBA on the 47 mm AXP90-X47 FULL and 26.1 on the 67 mm AXP120-X67, and ID-COOLING gives the 45 mm IS-40X V3 a 35.2 dB(A) maximum. No maker states where its microphone stood, so each brand is ranked alone.

On this page
  1. How we chose
  2. Our picks
  3. How to choose
  4. Comparison
  5. FAQs
  6. Bottom line
  7. Review history

A quick look at the quietest low profile CPU coolers

Fit the Low-Noise Adaptor from the box and Noctua's 65 mm NH-L9x65 falls from 23.6 to 14.8 dB(A), the lowest figure in Noctua's slim range. The fan slows from 2500 to 1800 RPM to get there, and Noctua ties that setup to CPUs of up to 65 W.

A low profile cooler trades height for heatsink. A slim fan, sometimes only 14 or 15 mm thick, rides on a short fin stack so the whole thing fits under a small form factor case panel. The picks run from 37 to 70 mm tall, with one at 77 mm for comparison.

Four makers print noise four ways. Noctua gives a figure for each cooler with its fan and a second with the speed limiting adaptor, Thermalright one inside the fan's spec block, be quiet! three load points and ID-COOLING a single maximum. Not one gives a microphone distance, so a figure here only ever meets figures from the same brand, and each height is the one its maker prints.

How we chose these low profile coolers

A pick needed two things: a decibel number printed by the cooler's maker for a current US model, and an Amazon listing for that exact model showing stock when checked on November 7, 2026.

The sources were Noctua's infosheets and specification pages, Thermalright's AXP product pages, ID-COOLING's IS-40X V3 page and be quiet!'s Pure Rock LP and Shadow Rock LP pages. Noctua's site and be quiet!'s English site answered our requests with bot checks, so the Noctua spec pages and both be quiet! pages are Internet Archive copies from May to October 2026, while the Noctua infosheets are live. Scythe's Japanese site served its home page for every Big Shuriken 3 address we tried, and the European Scythe address now shows an unrelated site, which leaves Scythe out. Cooler Master and Alpenföhn low profile models are not covered in this edition.

No maker here prints a US price, so none is listed. Every figure and height is copied as printed, with the fan speed or adaptor it names.

QuietSpecs' picks of the quietest low profile CPU coolers

Prices as of Nov 12. Product prices and availability are accurate as of the date/time indicated and are subject to change.

14.8 dB(A) on its adaptor, lowest in Noctua's slim range

Noctua NH-L9x65

Noctua NH-L9x65
  • Noise: 23.6 dB(A) max, 14.8 with L.N.A. (Noctua infosheet)
  • Price: $69.95 at Amazon, checked Nov 12
  • Best for: A 65 W chip in a case with 65 mm or more of cooler room
  • Skip it if: The case clears less than 65 mm

Two figures sit on the NH-L9x65 infosheet under "Max. acoustical noise": 23.6 dB(A) with the fan running to 2500 RPM, and 14.8 dB(A) at 1800 RPM with the Low-Noise Adaptor that ships in the box. No Noctua low profile cooler prints a lower one.

The cooler is 65 mm tall with its 14 mm thick fan, carries four heatpipes, and keeps a 95 x 95 mm footprint that Noctua says leaves RAM slots clear on Intel boards.

Check price at Amazon

A 120 mm fan in 70 mm of height

Noctua NH-L12S

Noctua NH-L12S
  • Noise: Full speed 23.9 dB(A), L.N.A. 16.8 (Noctua infosheet)
  • Price: $74.95 at Amazon, checked Nov 12
  • Best for: A case with 70 mm of room and space for a wider heatsink

Of Noctua's low profile coolers, only the NH-L12S fits a 120 mm fan and still stays at 70 mm, provided the fan sits under the fins.

Its infosheet reads "Max. acoustical noise 23.9 dB(A)" for a 1850 RPM fan, falling to 16.8 dB(A) at 1400 RPM on the adaptor. Mount the fan above the fins and the height becomes 87 mm, which Noctua says clears RAM of up to 45 mm.

Check price at Amazon

Thinnest for AM5, 37 mm

Noctua NH-L9a-AM5

Noctua NH-L9a-AM5
  • Noise: 23.6 dB(A) max (Noctua specification page)
  • Price: $49.95 at Amazon, checked Nov 12
  • Best for: A slim AM5 build where every millimetre of height counts
  • Skip it if: The Ryzen chip runs hot; Noctua scores this cooler 61 on its NSPR scale against 67 for the NH-L9x65

At 37 mm with the fan, the NH-L9a-AM5 shares the title of thinnest cooler here.

Its specification page lists "Acoustical noise (max.) 23.6 dB(A)" for the NF-A9x14 HS-PWM fan at up to 2500 rpm, the same as the taller NH-L9x65, and no adaptor figure, though the adaptor is in the box.

The chromax.black version's infosheet fills the gap with 14.8 dB(A).

Check price at Amazon

The Intel twin, also 37 mm

Noctua NH-L9i-17xx

Noctua NH-L9i-17xx
  • Noise: 23.6 dB(A) max (Noctua specification page)
  • Price: $49.95 at Amazon, checked Nov 12
  • Best for: A thin Intel build in a case that takes about 40 mm
  • Skip it if: Cooling headroom counts for more than a low height

Same height as the AM5 model, same fan, same "Acoustical noise (max.) 23.6 dB(A)" at up to 2500 rpm.

The page names LGA1700, LGA1851 and LGA1954, and like its AMD sibling it prints no Low-Noise Adaptor figure even with the adaptor in the scope of delivery.

Check price at Amazon

Thermalright's 47 mm cooler, 22.4 dBA on the fan

Thermalright AXP90-X47 FULL low profile cooler

Thermalright AXP90-X47 FULL low profile cooler
  • Noise: 22.4 dBA, fan only, rated 2700 RPM (Thermalright)
  • Price: $35.90 at Amazon, checked Nov 12
  • Best for: A slim ITX build where Thermalright's tallest options will not fit

The "Noise Level 22.4 dBA" on this page belongs to the TL-9015R fan at a rated 2700 RPM, inside the fan's spec block, not to the whole cooler. A 32 mm heatsink plus the 15 mm fan makes 47 mm.

The FULL version weighs 520 g with the fan, against 310 g for the plain AXP90-X47.

Check price at Amazon

Thermalright's 120 mm option at 67 mm

Thermalright AXP120-X67

Thermalright AXP120-X67
  • Noise: 26.1 dBA, fan only, rated 1800 RPM (Thermalright)
  • Price: $29.90 at Amazon, checked Nov 12
  • Best for: More heatsink than the AXP90 in a case that takes 67 mm
  • Skip it if: The AXP90's lower 22.4 dBA fan figure counts for more than a bigger heatsink

Here the 92 mm fan gives way to a 120 mm TL-C12015 over six heatpipes, listed at "Noise Level 26.1 dBA" with a rated 1800 RPM, 3.7 dBA above the AXP90 fans on Thermalright's other pages.

A 52 mm heatsink and 15 mm fan come to 67 mm, and the page asks you to check case and RAM clearance first.

Check price at Amazon

ID-COOLING's lone low profile page, 45 mm

ID-COOLING IS-40X V3

ID-COOLING IS-40X V3
  • Noise: 35.2 dB(A) max (ID-COOLING page)
  • Price: $26.99 at Amazon, checked Nov 12
  • Best for: A 45 mm slot where the Noctua 37 mm coolers lack heatsink
  • Skip it if: A low printed figure is the first test

"Noise 35.2dB(A) Max." is all the IS-40X V3 page offers on sound, beside a fan speed range of 800 to 2800 RPM and no word on where in that range the figure sits.

No other ID-COOLING low profile page was checked, so it stands alone in its group. The cooler is 45 mm tall overall, rated at 100 W, with four direct touch heatpipes.

Check price at Amazon

How to choose

Which low profile CPU cooler is the quietest?

Within Noctua's range, the NH-L9x65, at 14.8 dB(A) with the adaptor. No other maker's figure can be ranked against it.

MakerCoolerPrinted figureCondition
NoctuaNH-L9x6514.8 dB(A)Low-Noise Adaptor
NoctuaNH-L12S16.8 dB(A)Low-Noise Adaptor
NoctuaNH-L9x65, NH-L9a-AM5, NH-L9i-17xx23.6 dB(A)Full speed
NoctuaNH-L12S23.9 dB(A)Full speed
ThermalrightAXP90-X47 FULL22.4 dBAFan only
ThermalrightAXP120-X6726.1 dBAFan only
ID-COOLINGIS-40X V335.2 dB(A)Maximum

Thermalright's 22.4 looks lower than Noctua's 23.6. It describes a fan by itself, though, a different quantity from Noctua's cooler figure.

Heights run from 37 to 70 mm

Noctua's two NH-L9 coolers are the thinnest picks and the NH-L12S, fan below the fins, the tallest. Every height in this table is the maker's, fan included.

CoolerHeight with fan
Noctua NH-L9a-AM5 and NH-L9i-17xx37 mm
ID-COOLING IS-40X V345 mm
Thermalright AXP90-X47 FULL47 mm
Thermalright AXP90-X53 BLACK53 mm
Noctua NH-L9x6565 mm
Thermalright AXP120-X6767 mm
Noctua NH-L12S70 mm, or 87 mm with the fan on top
Noctua NH-L12Sx7777 mm by its infosheet

Measure your case's quoted cooler clearance before choosing, and leave a few millimetres spare. Our PC case guide lists cooler clearance for the cases it covers.

A thinner Noctua is not a louder one

At full speed the 37 mm NH-L9 coolers and the 65 mm NH-L9x65 print the same 23.6 dB(A), from one 92 mm fan model spinning up to 2500 rpm. What differs is the metal under the fan. The 37 mm pair has two heatpipes and a 23 mm heatsink, the NH-L9x65 four heatpipes and a 51 mm one. Noctua's NSPR performance score follows the metal: 59 for the NH-L9i-17xx, 61 for the NH-L9a-AM5 and 67 for the NH-L9x65. A cooler with more headroom reaches a given temperature at a lower fan speed, and lower speed is where the quiet comes from.

That last step stays a reasoned guess. Noctua prints nothing between idle and full speed.

The Low-Noise Adaptor takes 7 to 9 dB off

The adaptor works by capping fan speed: 8.8 dB comes off the printed figure on the NH-L9x65, and 7.1 on the NH-L12S.

CoolerFan speed, bare to adaptorPrinted figure, bare to adaptor
NH-L9x652500 to 1800 RPM23.6 to 14.8 dB(A)
NH-L12S and NH-L12Sx771850 to 1400 RPM23.9 to 16.8 dB(A)

Noctua attaches a condition to the first: the adaptor "makes it possible to achieve near-silent setups using CPUs with up to 65W TDP." Pair it with a hotter chip and the capped fan may not keep up.

The NH-L9a-AM5 and NH-L9i-17xx ship with the same adaptor, yet their spec pages print no figure for it. The chromax.black AM5 version's infosheet does, 14.8 dB(A) at 1800 RPM. Every other Noctua cooler and fan figure, with and without the adaptor, is on our Noctua decibel page.

Why can't Noctua and Thermalright be ranked together?

They print different things. Noctua's figure belongs to the cooler with its fan, while Thermalright's sits inside a "FAN Spec" block, and neither names a distance, room or standard.

Every AXP90 page carries "Noise Level 22.4 dBA" with the fan rated "2700 RPM±10% (MAX)", whether the heatsink is 21, 32 or 38 mm tall. That pattern fits a fan figure copied from page to page better than a test of each cooler. Noctua's figures come from an in-house bench, and nothing printed describes it. On that footing a 1 dB gap between brands is not a result, and the picks above stay in separate groups. The wider CPU cooler guide runs into the same wall with full size towers.

Partial load figures come only from be quiet!

Both be quiet! low profile coolers carry three figures, at half, three quarter and full PWM.

CoolerHeightHalf / three quarter / full PWM
Pure Rock LP45 mm13.3 / 23.8 / 30.6 dB(A)
Shadow Rock LP50 or 75 mm14.8 / 18.6 / 25.5 dB(A)

The Pure Rock LP holds both ends of that spread, 13.3 at half speed and 30.6 at full. Neither cooler made the picks: the Amazon listing for the Pure Rock LP names neither LP nor BK034, and the Shadow Rock LP had only a low stock listing on November 7, 2026.

Spec sheets disagree on height

Two coolers carry two heights from one maker. A third maker leaves the fan out of its height altogether.

Noctua's NH-L12Sx77 infosheet calls it 77 mm tall with the fan below the fins, while its specification page lists "Total height 93 mm" with the fan and 77 without. be quiet!'s Shadow Rock LP page gives "134 x 122 x 50" in one table and "134 x 122 x 75" in another.

Thermalright gives heatsink height alone: 32, 38 and 52 mm for the AXP90-X47, AXP90-X53 and AXP120-X67. Add 15 mm of fan and you reach the number in each name.

How the quietest low profile CPU coolers compare

ProductNoiseHeightFootprintFanSocketsPrice
Noctua NH-L9x6523.6 dB(A) max, 14.8 with L.N.A. (Noctua infosheet)65 mm with fan, 51 mm heatsink only95 x 95 mm1, NF-A9x14 92 mm slim, 2500 RPMAM5, AM4, LGA1851, LGA1700, LGA1200, LGA115x$69.95
Noctua NH-L12SFull speed 23.9 dB(A), L.N.A. 16.8 (Noctua infosheet)70 mm fan underneath, 87 mm fan on top146 x 128 mm1, NF-A12x15 120 mm slim, 1850 RPMAM5, AM4, LGA1851, LGA1700, LGA1200, LGA115x$74.95
Noctua NH-L9a-AM523.6 dB(A) max (Noctua specification page)37 mm with fan, 23 mm without114 x 92 mm1, NF-A9x14 HS-PWM 92 mm slim, 0 to 2500 rpmAM5$49.95
Noctua NH-L9i-17xx23.6 dB(A) max (Noctua specification page)37 mm with fan, 23 mm without95 x 95 mm1, NF-A9x14 HS-PWM 92 mm slim, 0 to 2500 rpmLGA1700, LGA1851, LGA1954$49.95
Thermalright AXP90-X47 FULL22.4 dBA, fan only, rated 2700 RPM (Thermalright)47 mm, 32 mm heatsink plus 15 mm fan94.5 x 95 mm1, TL-9015R 92 mm slimAM5, AM4, LGA1851, LGA1700, LGA1200, LGA115x$35.90
Thermalright AXP120-X6726.1 dBA, fan only, rated 1800 RPM (Thermalright)67 mm, 52 mm heatsink plus 15 mm fan123.5 x 120 mm1, TL-C12015 120 mm slimAM5, AM4, LGA1851, LGA1700, LGA1200, LGA115x, 2011, 2066$29.90
ID-COOLING IS-40X V335.2 dB(A) max (ID-COOLING page)45 mm overall94 x 101 mm1, 92 mm slim, 800 to 2800 RPMAM5, AM4, LGA1851, LGA1700, LGA1200, LGA115x$26.99

Prices as of Nov 12. Product prices and availability are accurate as of the date/time indicated and are subject to change.

Frequently asked questions

What is the quietest low profile CPU cooler?

Within Noctua's range, the NH-L9x65: 14.8 dB(A) with the adaptor slowing its fan to 1800 RPM, 65 mm tall. Thermalright's lowest is 22.4 dBA for the AXP90 fans. One is a cooler figure and the other a fan figure, so the two never share a ranking here.

Does the Low-Noise Adaptor work on the NH-L9 coolers?

Yes, and every NH-L9 ships with one. On the NH-L9x65 the fan drops from 2500 to 1800 rpm and the printed figure from 23.6 to 14.8 dB(A), a setup Noctua rates for CPUs of up to 65 W. The NH-L9a-AM5 and NH-L9i-17xx pages give no adaptor figure.

Why does Thermalright's height not match the model name?

The spec block gives heatsink height alone: 32 mm for the AXP90-X47, 38 for the AXP90-X53 and 52 for the AXP120-X67. Add the 15 mm fan and you reach the 47, 53 and 67 in the names.

Can I compare a Noctua dB(A) figure with a Thermalright dBA figure?

Not safely. Noctua prints a figure for the cooler with its fan, Thermalright one inside the fan's spec block, and neither names a distance or standard. Our explainer on comparing ratings covers why that rules out a cross-brand ranking.

The bottom line

Short coolers ought to be the loud ones. A thin fan has to spin fast to push air through a shallow fin stack, and Noctua's 92 mm slim fan does run to 2500 RPM. Yet its 37 mm coolers list the same 23.6 dB(A) as the 65 mm one. Heat capacity is what separates them.

For a 65 W chip in a case with 65 mm of room, buy the NH-L9x65 and fit the adaptor. Noctua prints 14.8 dB(A) for that setup, and no other cooler here ties a quiet figure to a stated CPU class. Do not hold a Thermalright figure up against it. One is a fan alone, the other a whole cooler, and neither maker names a distance.

Stanley Alu, founder and editor

What we also considered

These are worth knowing about, and why they didn't make the list.

  • Noctua NH-L12Sx77

    Six heatpipes and the NH-L12S's 23.9 and 16.8 dB(A), but 77 mm tall by its infosheet, and Noctua's spec page lists 93 mm with the fan.

    See it at Amazon

  • Thermalright AXP90-X53 BLACK

    A 38 mm heatsink brings this one to 53 mm, with the same 22.4 dBA fan figure as the AXP90-X47 FULL.

    See it at Amazon

  • be quiet! Pure Rock LP

    A 45 mm cooler with 13.3 / 23.8 / 30.6 dB(A) printed at half, three quarter and full PWM, but the Amazon listing we found names neither LP nor BK034.

    Search Amazon for this model

  • be quiet! Shadow Rock LP

    Three PWM figures, 14.8, 18.6 and 25.5 dB(A), on a page that prints both 50 and 75 mm heights; the only Amazon listing was low on stock.

    Search Amazon for this model

How we reviewed this article

Every statement here comes from the 14 maker documents, standards and agency pages listed under Sources, quoted where the wording matters. We did not measure, inspect or repair anything ourselves. Each substantive revision is dated below. How we work

  1. Current version

    First published, written by Stanley Alu.

Sources

All 14 sources
Manufacturer pages and manuals for every product

Related guides

The quietest CPU coolers

Most cooler makers publish one decibel figure, at full speed. A few publish figures at partial load, which is where a cooler actually runs. See the quietest air, low profile and liquid coolers.

Noctua fan noise dB with and without the Low-Noise Adaptor

The NF-S12B redux-700 lists the lowest full-speed figure of any 120mm Noctua, 6.8 dB(A) at 700 RPM, and the NF-S12A ULN the lowest with its Low-Noise Adaptor, 6.7 dB(A) at 600 RPM. Nearly every Noctua infosheet gives the figure twice, at full speed and with the adaptor in the box, beside airflow and static pressure.

The quietest PC cases, by the fans they ship with

No case maker publishes a noise figure for the case itself. NZXT, Thermaltake and Lian Li publish ratings for the fans in the box, from 22.9 to 35.8 dBA at a stated speed. See which cases ship with the lowest rated fans, and the brands that print nothing.