The Core i7-5820K is a six-core Haswell-E chip for X99 boards, rated at 140W and sold without a cooler, and many now live on as cheap workstations. This guide to the best CPU coolers for i7 5820K systems lists six coolers that still name LGA 2011 support, since most current models dropped the socket.
Quick verdict
The Thermalright Peerless Assassin 120 is the best value for an i7-5820K: Thermalright’s page lists LGA 2011-3, it is a 157mm dual tower with six heat pipes, and it sells for about $36. Overclockers who want more fan speed should look at the Phantom Spirit 120 EVO, and the Cooler Master ML240L RGB V2 is the liquid choice.
| Cooler | Type | Height or radiator | LGA 2011-3 listed | Best for | Amazon US, Nov 2026 |
|---|---|---|---|---|---|
| Thermalright Peerless Assassin 120 | Dual-tower air | 157mm | Yes (maker page) | Best value | about $36 |
| Thermalright Phantom Spirit 120 EVO | Dual-tower air | 157mm | LGA 2011 in listing | Overclocking on air | about $47 |
| Noctua NH-U9S | Compact tower | 125mm | LGA 2011-v3 in listing | Small cases, quiet | about $70 |
| Thermalright SI-100 Black | Top-flow air | 74.8mm heatsink | Yes (maker page) | Low cases, VRM airflow | about $27 |
| Cooler Master MasterLiquid ML240L RGB V2 | 240mm AIO | 277 x 119.6 x 27.2mm | Yes (2011-v3) | Liquid cooling | about $90 |
| Thermalright AXP120-X67 | Low-profile air | 67mm | Yes (2011, 2066) | Compact X99 builds | about $33 |
How we selected coolers for the i7-5820K
Intel’s specification page lists the i7-5820K with six cores and 12 threads, 3.3GHz base and 3.6GHz turbo clocks, a 140W TDP and a 66.8 Tcase, launched in the third quarter of 2014. The page states the boxed processor ships without a fan or heatsink, and lists the socket as FCLGA2011, the X99 variant usually called LGA 2011-3 or 2011-v3.
That socket is the main problem. Most new coolers list LGA 1851, 1700 and 115x but not LGA 2011, so each pick had to name LGA 2011 or 2011-3 on its maker page or Amazon listing. We then checked for published heights and rating counts. This is a research roundup from spec pages and Amazon US data from November 2026, with no temperatures from our own testing.
A 140W six-core needs more cooler than a mainstream quad core, especially once you raise its unlocked multiplier. The list therefore centers on dual towers and an AIO, with three compact options for smaller cases and for boards whose VRMs benefit from airflow.
Best CPU coolers for i7 5820K builds, reviewed
Each review covers the build it suits, the verified specs, the Amazon rating snapshot and its limits. Ratings and prices are November 2026 snapshots and will change. Where only the Amazon listing names LGA 2011, we say so, and you should confirm the X99 bracket is in the box before installing.
Thermalright Peerless Assassin 120
The standard Peerless Assassin 120, not the SE, is our top pick because Thermalright’s own page lists LGA 2011, 2011-3 and 2066. The page gives 125 x 135 x 157mm dimensions, 750g weight, six 6mm heat pipes and TL-C12 120mm fans rated at 1550 RPM, 25.6 dBA and 66.17 CFM, plus LGA 115x, 1200, 1700 and 1851 and AM4 and AM5.
The Amazon listing names dual 120mm PWM fans. That matters, because the popular SE version’s page lists only LGA 115X, 1200, 1700 and 1851, so buying the wrong variant would leave you without X99 hardware. A six-pipe dual tower gives a 140W six-core real headroom at modest fan speeds.
It was rated 4.7 out of 5 from about 190 Amazon ratings and listed around $36 on Amazon US as of November 2026. Its 157mm height suits most full ATX towers used for X99, but check clearance and the first DIMM slot, since X99 boards place RAM on both sides of the socket.
- Pro: maker page explicitly lists LGA 2011-3 and 2066
- Pro: dual tower with two fans for about $36
- Con: easily confused with the SE, which lacks LGA 2011
- Con: warranty not stated on the maker page
Buy it if you want the best value air cooler for a stock or overclocked 5820K. Skip it if your case is under 160mm.
Thermalright Phantom Spirit 120 EVO
The Phantom Spirit 120 EVO is for X99 overclockers who want more fan headroom. The Amazon listing gives 125 x 135 x 157mm, seven blackened 6mm heat pipes and two TL-K12 fans at up to 2150 RPM, 69 CFM and 27 dB, and its title lists Intel 1700, 1150, 1151, 1200, 2011 and 1851 plus AM4 and AM5.
One extra heat pipe and faster fans over the Peerless Assassin 120 suit an overclocked six-core, where power climbs well above the 140W TDP. The listing names LGA 2011 rather than 2011-3 specifically, so confirm the included Intel hardware includes the threaded studs for an X99 socket before you remove your old cooler.
It was rated 4.8 out of 5 from about 520 Amazon ratings and listed around $47 on Amazon US as of November 2026. At full speed its fans will be louder than slower 1500 RPM designs, so set a fan curve.
- Pro: seven heat pipes and 2150 RPM fans
- Pro: higher rating count than the PA120
- Con: listing says LGA 2011, not 2011-3 specifically
- Con: warranty not confirmed on a maker page
Buy it if you overclock the 5820K on air. Skip it if quiet matters more than peak headroom.
Noctua NH-U9S
The NH-U9S is for compact X99 builds and quiet stock operation. Its Amazon listing gives a 125mm height, an NF-A9 92mm PWM fan with a Low-Noise Adaptor and a six-year warranty, and the listing’s socket field includes Intel LGA 2011-v3 along with LGA 1150. A retailer spec sheet lists five dual heat pipes.
The listing’s bullets mention current sockets only, so the LGA 2011-v3 entry comes from the spec field; Noctua’s square-ILM X99 support for this model should still be confirmed against the box contents. As a 92mm tower it suits a 5820K at stock better than an aggressive overclock.
It was rated 4.8 out of 5 from about 1,800 Amazon ratings and listed around $70 on Amazon US as of November 2026. Its small size leaves all eight DIMM slots on a typical X99 board accessible, which larger towers may not.
- Pro: six-year warranty and Noctua mounting quality
- Pro: 125mm height and good RAM clearance
- Con: 92mm fan limits overclocking headroom
- Con: LGA 2011-v3 support appears only in the spec field
Buy it if you run the 5820K at stock in a compact case. Skip it if you plan a big overclock.
Thermalright SI-100 Black
The SI-100 Black is a top-flow cooler for low cases and X99 boards where VRM airflow matters. Thermalright’s page lists a 120 x 108 x 74.8mm heatsink, six 6mm heat pipes on a nickel-plated C1100 copper base, a TL-E12B 120mm fan rated at 2000 RPM, 27.7 dBA and 72.37 CFM, and Intel LGA 115x, 1200, 1700, 1851, 2011 and 2066 plus AM4 and AM5.
Because the fan blows down toward the board, it also moves air across the area around the socket, which can help VRM heatsinks on boards running a six-core chip. The total height with the fan is not stated on the page, so add the 25mm fan to the heatsink figure when checking clearance.
It was rated 4.5 out of 5 from about 110 Amazon ratings and listed around $27 on Amazon US as of November 2026. A top-flow design has less headroom than a dual tower, so this suits stock use or a mild overclock.
- Pro: maker page lists LGA 2011 and 2066
- Pro: top-down airflow over the socket area
- Con: less headroom than a dual tower
- Con: smaller review base and no stated warranty
Buy it if your case cannot take a tall tower or your VRM runs warm. Skip it for heavy overclocking.
Cooler Master MasterLiquid ML240L RGB V2
The ML240L RGB V2 is the liquid choice for an i7-5820K. The Amazon listing gives a 277 x 119.6 x 27.2mm radiator, a third-generation dual-chamber pump and two SickleFlow 120mm RGB PWM fans, and lists Intel LGA 2066, 2011-v3, 2011, 1366, 1200 and 115x plus AMD AM4 and older AMD sockets. LGA 1700 requires a separate kit.
That broad Intel list makes it one of the few modern AIOs with explicit LGA 2011-v3 support. A 240mm radiator clears space around the socket and the eight DIMM slots of a typical X99 board, which helps in builds with tall memory.
It was rated 4.6 out of 5 from about 9,600 Amazon ratings and listed around $90 on Amazon US as of November 2026, the largest review base in this list. Confirm your case has a 240mm mount at the top or front before ordering.
- Pro: explicit LGA 2011-v3 support
- Pro: very large review base
- Con: needs a 240mm mount
- Con: costs much more than the PA120
Buy it if you prefer liquid or have tall RAM around the socket. Skip it if a dual tower fits your case.
Thermalright AXP120-X67
The AXP120-X67 is for compact X99 builds, such as micro-ATX X99 boards in small cases. Thermalright’s page lists a 52mm heatsink plus a 120 x 120 x 15mm TL-C12015 fan for 67mm total, six 6mm heat pipes and Intel 115X, 1200, 1700, 1851, 2011, 2011-3 and 2066 plus AM4 and AM5.
Six heat pipes are unusual in a 67mm cooler, which gives a stock 5820K some margin in a small case. Still, a 140W six-core is a heavy load for any low-profile design, so expect the slim fan to run fast under long all-core work and avoid overclocking.
The Amazon listing for this model was rated 4.3 out of 5 from about 75 ratings and listed around $33 on Amazon US as of November 2026. The small review base is a reason to read recent reviews before buying.
- Pro: explicit LGA 2011-3 and 2066 support on the maker page
- Pro: 67mm height with six heat pipes
- Con: limited headroom for a 140W chip
- Con: small review base
Buy it if your X99 build is compact and you stay at stock. Skip it if your case fits a tower.
Buying guide for an i7-5820K cooler
X99 cooling is mostly about finding coolers that still support the socket, then matching headroom to your overclocking plans. The checks below cover socket hardware, headroom, RAM and case clearance, and fan control on X99 boards, the points that most often decide whether a cooler is right.
Confirm LGA 2011-3 hardware
LGA 2011-3 uses a square independent loading mechanism with its own threaded mounting points, a different design from mainstream LGA 115x and LGA 1700 sockets. Noctua’s spec tables, for example, distinguish Square ILM from the Narrow ILM found on many server boards.
Many coolers now list only LGA 1851, 1700 and 115x, including the popular Peerless Assassin 120 SE. Check the maker page or listing for LGA 2011 or 2011-3 and confirm the box contains the X99 studs before removing your old cooler.
Match headroom to your overclock
At stock, the 5820K’s 140W TDP is already higher than most mainstream chips, so a basic four-pipe tower is a poor match. Dual towers like the PA120 and Phantom Spirit 120 EVO, or the ML240L RGB V2, give room for added voltage and an all-core overclock.
Compact options like the NH-U9S, SI-100 and AXP120-X67 are best kept for stock settings. If you overclock, raise the multiplier gradually and watch temperatures under a sustained load before settling on a setting.
RAM layout and case clearance
X99 boards usually have DIMM slots on both sides of the socket, so dual towers can overhang memory on one or both sides. Check RAM height against the cooler’s stated clearance, or choose the top-flow SI-100 or the ML240L RGB V2 if your memory kit has tall heat spreaders or RGB light bars.
Heights here range from 67mm to 157mm. A report on Noctua’s survey of over 100 cases found more than half deviated from their listed cooler clearance, so measure your own case with the side panel off.
Fan headers and noise
Many X99 boards have several fan headers, so two-fan coolers can use CPU_FAN and CPU_OPT, or a splitter on one header. Use PWM control and a gentle fan curve, since a six-core chip under a long all-core load can push the fans hard and make the system loud.
Rated maximum fan noise here ranges from 25.6 dBA for the PA120’s fans to 27.7 dBA for the SI-100’s. These are each maker’s figures and not directly comparable across brands.
FAQ
These answers cover the most common i7-5820K cooling questions, including socket support, whether the box includes a cooler, and how much headroom an overclock needs. They draw on Intel’s spec page and the maker and Amazon data above, with no temperature claims or invented test results.
Does the i7-5820K come with a cooler?
No. Intel’s specification page states the boxed i7-5820K ships without a fan or heatsink, so you need an aftermarket cooler. With a 140W TDP, a dual tower such as the Thermalright Peerless Assassin 120 or a 240mm AIO is the sensible starting point for most X99 builds.
Why do most new coolers not fit the i7-5820K?
X99 uses LGA 2011-3 with a square ILM, while most coolers now ship hardware only for LGA 1851, 1700, 1200 and 115x plus AMD sockets. The popular Peerless Assassin 120 SE is an example. Always check for LGA 2011 or 2011-3 on the maker page or listing before you buy.
Which of the best CPU coolers for i7 5820K is best for overclocking?
The Thermalright Phantom Spirit 120 EVO is the strongest air option here, with seven heat pipes and 2150 RPM fans, and the ML240L RGB V2 is the liquid choice with explicit LGA 2011-v3 support. Results still depend on your chip, voltage and case airflow.
Conclusion
Buy the Thermalright Peerless Assassin 120 for an i7-5820K. Thermalright’s page lists LGA 2011-3, its dual tower and two fans handle a 140W six-core with room to overclock, and it costs about $36. Make sure you get the standard model, not the SE, and choose the ML240L RGB V2 only if you prefer liquid.
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