Micro ATX cases for LGA 1151 PCs come in every shape, from slim desktops to compact towers, and the cooler has to fit both the case and the crowded board around the socket. This guide to the best CPU coolers 1151 micro ATX builders can use sorts seven options by height, with verified 115x support and Amazon US data from November 2026.
Quick verdict
If your micro ATX case fits a 125mm tower, buy the Noctua NH-U9S: it clears the RAM and the top PCIe slot on most boards and has a six-year warranty. For slim cases, the Noctua NH-L12S at 70mm is the best low-profile choice, and the Thermalright Assassin X120 Refined SE is the value pick for cases that take 148mm.
| Cooler | Type | Height | Fan | LGA 1151 | Best for | Amazon US, Nov 2026 |
|---|---|---|---|---|---|---|
| ID-Cooling IS-55 Black | Low profile | 57mm | 120 x 15mm | Yes | Slim cases, budget | about $40, 4.5 stars, 837 ratings |
| Noctua NH-L9x65 | Low profile | 65mm | 92 x 14mm | Yes | Quiet small desktops | about $70, 4.7 stars, 2,972 ratings |
| Noctua NH-L12S | Low profile | 70mm | 120 x 15mm | Yes | Best low-profile overall | about $75, 4.7 stars, 1,943 ratings |
| Noctua NH-U9S | Compact tower | 125mm | 92mm | Yes | Best overall for micro ATX | about $70, 4.8 stars, 1,844 ratings |
| Noctua NH-D12L | Low dual tower | 145mm | 120mm | Yes | Hot K chips in compact towers | about $100, 4.8 stars, 675 ratings |
| Thermalright Assassin X120 Refined SE | Single tower | 148mm | 120mm | Yes | Budget compact towers | about $16, 4.7 stars, 1,860 ratings |
| Thermalright Aqua Elite 120 V3 | 120mm AIO | 120mm radiator | 120mm | Yes | Cases with a rear 120mm mount | about $35, 4.6 stars, 483 ratings |
Prices and ratings are Amazon US snapshots as of November 2026 and will change. Heights are total heights with fans as listed by Noctua, ID-Cooling and Thermalright or their Amazon listings.
How we selected these micro ATX coolers
Micro ATX boards pack the RAM slots, the first PCIe slot and the power circuitry close to the CPU socket, and micro ATX cases range from 60mm slim desktops to compact towers. So we sorted candidates by total height first, then checked each for LGA 115x mounting, RAM overhang and PCIe clearance.
Every pick lists LGA 1151 or LGA 115x support on its manufacturer page or Amazon listing as of November 2026. We excluded popular coolers that dropped 115x, and we kept models with large Amazon US rating pools so buyers have real owner feedback. We did not test these coolers ourselves.
We also matched each cooler to the chips this socket runs. Intel lists 65W for the Core i7-8700 and 95W for the i7-8700K and i9-9900K, and that power gap decides whether a low-profile cooler is enough or whether you need a tower.
Best CPU coolers 1151 micro ATX cases can fit, by height
The seven coolers below run from the shortest to the tallest, so you can stop reading once you pass your case’s limit. Each one explains the chips it suits, the board-area clearance it needs and how it compares with the next size up for an LGA 1151 micro ATX build.
ID-Cooling IS-55 Black
The IS-55 Black is the shortest cooler here and the budget choice for slim micro ATX desktops. ID-Cooling lists a 57mm height, a 120 x 120 x 15mm PWM fan, five 6mm heat pipes on a copper base, LGA 1851 to 115x plus AM5 and AM4 mounting, and a 150W rating it sets itself.
The Amazon listing quotes up to 54.6 CFM and 13.8 to 31.2 dB(A), and it was listed around $40 as of November 2026 with 4.5 stars from about 840 ratings. A 120mm fan in a 57mm package is unusual, which gives more fan area than most slim coolers this short.
Its wide 120mm footprint can overhang RAM on some boards, so check the memory slot position and use low-profile DIMMs. ID-Cooling’s page did not state a warranty. For a 95W K-series chip, expect fan noise to rise under sustained load.
- Pro: 57mm height with a 120mm fan
- Pro: five heat pipes and broad socket list
- Con: wide footprint can clash with tall RAM
- Con: warranty not stated
Buy it if your case caps cooler height near 60mm. Skip it if you need a quiet cooler for a K-series chip.
Noctua NH-L9x65
The NH-L9x65 is the quiet small-desktop pick. Amazon lists a 65mm total height, a slim NF-A9x14 92mm PWM fan, a footprint that does not overhang the RAM or PCIe slots on most current boards, NT-H1 paste, SecuFirm2 mounting for LGA 115x to 1851 plus AM5 and AM4, and a six-year warranty.
It was listed around $70 on Amazon US as of November 2026 with 4.7 stars from about 3,000 ratings. Noctua recommends it for CPUs with low to moderate heat output, which makes it a good match for a 65W Core i7-8700 or a Core i5 non-K chip.
The compact 92mm footprint is the main advantage on crowded micro ATX boards, since it stays clear of tall RAM. On a 95W K chip under full load, it will run its fan harder, so consider lowering the power limit if quiet operation is the goal.
- Pro: no RAM or PCIe overhang on most boards
- Pro: six-year warranty
- Con: small fan limits headroom
- Con: priced well above the IS-55
Buy it if you want a quiet, RAM-friendly cooler under 70mm. Skip it if you run an unlocked chip hard.
Noctua NH-L12S
The NH-L12S is the strongest low-profile option here. Retailer specs list a 70mm height in low-profile mode, an NF-A12x15 120mm slim fan, LGA 115x to 1851 plus AM5 and AM4 support and a six-year warranty, and Amazon adds four heat pipes and NT-H1 paste.
A retailer lists RAM clearance of 35mm with the fan in low-profile position and 48mm with the fan raised, which adds height. That flexibility helps on micro ATX boards where the RAM sits close to the socket. Mounting the fan on top raises total height to 95mm, according to the same retailer.
It was listed around $75 on Amazon US as of November 2026 with 4.7 stars from about 1,900 ratings. For 65W chips it is a comfortable fit, and Noctua’s listing positions it for a wide range of current CPUs. For a 95W K chip, it is the low-profile cooler with the most margin.
- Pro: 120mm fan and four heat pipes at 70mm
- Pro: flexible RAM clearance options
- Con: low-profile RAM limit of 35mm
- Con: most expensive low-profile pick here
Buy it if your case allows about 70mm and you want the most low-profile cooling. Skip it if your case fits a 125mm tower.
Noctua NH-U9S
The NH-U9S is our best overall pick for LGA 1151 micro ATX towers. Retailer and Amazon listings give a 125mm height, an NF-A9 92mm PWM fan with an optional second fan, five dual heat pipes, SecuFirm2 mounting for LGA 115x to 1851 plus AM5 and AM4, and a six-year warranty.
Noctua’s listing says it does not overhang the RAM or PCIe slots on most current boards, which matters on micro ATX layouts where the graphics card sits close to the socket. Its 125mm height also fits many compact towers that reject standard 150mm-plus coolers.
It was listed around $70 on Amazon US as of November 2026 with 4.8 stars from about 1,800 ratings. A tower moves heat to the rear exhaust instead of blowing down onto the board, which suits enclosed micro ATX cases. For 95W chips, a second fan adds headroom.
- Pro: 125mm fits many compact towers
- Pro: no RAM or PCIe overhang on most boards
- Con: 92mm fan is smaller than 120mm rivals
- Con: costs more than full-size budget towers
Buy it if your micro ATX case fits about 125mm. Skip it if your case fits 148mm and you want the cheapest option.
Noctua NH-D12L
The NH-D12L is a dual tower built for low cases. The Amazon listing gives a 145mm height, one NF-A12x25r 120mm fan, five heat pipes, full RAM compatibility on LGA 1700, 1200, 115x, AM4 and AM5, SecuFirm2 mounting including LGA 1851, an offset option and a six-year warranty.
It was listed at $99.95 on Amazon US as of November 2026 with 4.8 stars from about 680 ratings. That is a lot of money for an older system, but it brings dual-tower capacity into compact towers that cannot take 155mm coolers, which suits a Core i9-9900K or an overclocked i7-8700K.
Its broad socket list also means you can move it to a newer micro ATX board later. If your case has room for 148mm, the much cheaper Assassin X120 Refined SE handles stock 95W chips well, so the NH-D12L earns its price mainly on hot or overclocked K-series chips.
- Pro: dual tower at 145mm
- Pro: 100 percent RAM compatibility and six-year warranty
- Con: expensive for an older platform
- Con: wider than single towers
Buy it if you have a hot K chip in a compact tower near 145mm. Skip it if you run a 65W chip.
Thermalright Assassin X120 Refined SE
The Assassin X120 Refined SE is the value pick for micro ATX towers with about 150mm of clearance. Thermalright lists a 148mm height, four 6mm heat pipes, one TL-C12C 120mm fan at 1,550 rpm and LGA 115x to 1851 plus AM5 and AM4 support in its mounting kit.
The Amazon listing gives a 125 x 71 x 148mm size, so the heatsink is slim enough to avoid most RAM on micro ATX boards. It was listed around $16 on Amazon US as of November 2026 with 4.7 stars from about 1,900 ratings.
At that price it is an easy match for a 65W chip or a stock 95W K chip. Check the gap between the socket and the first PCIe slot, though, since a 125mm-wide fan can sit close to a large graphics card backplate on some micro ATX layouts.
- Pro: very low price
- Pro: slim 71mm depth
- Con: 148mm rules out many compact cases
- Con: no warranty length stated by Thermalright
Buy it if your case fits 148mm and you want to spend as little as possible. Skip it if your limit is below 150mm.
Thermalright Aqua Elite 120 V3
The Aqua Elite 120 V3 is a 120mm AIO for micro ATX cases with a rear 120mm fan mount but little height above the CPU. The Amazon listing names LGA 1150, 1151, 1155, 1156, 1200, 1700 and 1851 plus AM4 and AM5, with TL-C12B-S V2 fans rated at 1,500 rpm and 25.6 dBA.
It was listed around $35 on Amazon US as of November 2026 with 4.6 stars from about 480 ratings. The listing mentions dual fans, which would mean push-pull on one radiator, but it is not fully clear, so check the box contents. Radiator thickness was not stated in the data we checked.
A 120mm radiator offers limited surface area, and the AIO adds a pump that a tower does not need. It makes sense when the case can only take a short pump block over the CPU and a 120mm radiator at the rear, or when tall RAM blocks towers.
- Pro: clears tall RAM and short case side panels
- Pro: low price for an AIO
- Con: small radiator and an added pump
- Con: fan count and thickness unclear in the listing
Buy it if your case has a rear 120mm mount but limited height. Skip it if a 125mm tower fits.
Micro ATX cooler buying guide for LGA 1151
Fitting a cooler in a micro ATX case means checking three dimensions at once: height to the side panel, clearance over the RAM and distance to the first PCIe slot. The sections below walk through each one, along with mounting and chip power, so the cooler you order actually fits and runs quietly.
Measure your case height
Start with the maximum cooler height in your case manual, then measure from the motherboard surface to the side panel if you can. A Noctua study reported by The FPS Review in August 2026 found that 56 of more than 100 measured cases differed significantly from their listed clearance.
Leave a margin of a few millimeters. The picks here sit at 57, 65, 70, 125, 145 and 148mm, so you can choose the tallest option that still clears with room to spare, since taller coolers generally carry more heatsink.
RAM and PCIe clearance on small boards
Micro ATX boards often place the RAM slots and the first PCIe slot close to the socket. Low-profile coolers with wide 120mm fans, such as the IS-55 and NH-L12S, can sit over the memory, so check their listed RAM clearance and use low-profile DIMMs if needed.
Noctua lists the NH-U9S, NH-L9x65 and NH-D12L as avoiding RAM overhang on most boards. Also check where the graphics card sits, since a tower that leans toward the PCIe slot can touch a large card’s backplate.
Socket and mounting
LGA 1151 uses the 75 x 75mm LGA 115x hole pattern, while LGA 1700 and 1851 use 78 x 78mm, according to Wikipedia’s LGA 1700 page. Every cooler here lists 115x hardware, so you do not need adapters, but confirm the kit before you remove the old cooler.
Some low-profile coolers mount from the back of the board, which means removing the motherboard on some cases. Plan for that if your case has no cutout behind the socket.
Match the cooler to your chip
Intel lists the Core i7-8700 at 65W, and the i7-8700K and i9-9900K at 95W, with no cooler in the box for the K models. Low-profile coolers suit the 65W chips best. For K chips, choose a tower or the NH-L12S and expect higher fan speeds under sustained load, especially in enclosed cases.
If your case limits you to a small cooler but you own a K chip, setting a lower power limit in the BIOS reduces heat and noise. That is often a better trade than forcing an oversized cooler into a cramped case.
FAQ
These answers cover the questions people ask when fitting a cooler into a small LGA 1151 build. They rely on Intel specs and the manufacturer and Amazon US data collected in November 2026, and they avoid temperature claims we could not verify from a published source for these specific coolers.
What are the best CPU coolers 1151 micro ATX cases under 70mm can take?
The Noctua NH-L12S at 70mm is the strongest option, followed by the NH-L9x65 at 65mm and the ID-Cooling IS-55 Black at 57mm. Pick the NH-L9x65 if RAM clearance is tight, and the IS-55 if your case limit is closer to 60mm or your budget is tight. All three list LGA 115x mounting.
Is a low-profile cooler enough for an i7-8700K?
It can run one at stock, but with little headroom. Intel rates the i7-8700K at 95W, and low-profile coolers like the NH-L9x65 are positioned for moderate heat loads. The NH-L12S has more margin, while a 125mm tower like the NH-U9S is a better fit if your case allows it.
Will these coolers fit a newer micro ATX board later?
Most of them will. The Noctua coolers, the IS-55, the Assassin X120 Refined SE and the Aqua Elite 120 V3 all list LGA 1700 or 1851 plus AM5 and AM4 support, so you can carry them to a newer micro ATX board if the case still fits. Keep the spare mounting parts from the box so the move is easy later.
Is a 120mm AIO better than a compact tower?
Not usually for cooling capacity. A 120mm radiator is small, and it adds a pump. A 120mm AIO is mainly useful when your case has a rear 120mm mount but too little height for a 125mm tower, or when tall RAM blocks low-profile coolers that would otherwise sit over the memory slots.
Conclusion
For LGA 1151 micro ATX towers, buy the Noctua NH-U9S: at 125mm it fits most compact cases, clears RAM and the top PCIe slot on most boards, and carries a six-year warranty. In slim desktops under 75mm, choose the Noctua NH-L12S instead, and the Assassin X120 Refined SE if 148mm fits.
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