How to Choose a CPU Cooler for a Custom PC [Performance / Features / Compatibility]

A CPU cooler is a part that efficiently cools CPU heat to keep CPU performance stable over long periods.

Among PC components, the CPU generates a lot of heat, so the CPU cooler keeps overall PC performance by cooling it properly.

If cooling is not sufficient for the CPU’s heat output, performance drops under long, heavy loads, processing takes longer, and games can feel heavy.

Also, heat is harmful to parts including the CPU, which can shorten lifespan.

This guide explains the knowledge needed for CPU coolers in a custom PC build, key functions, and how to choose from performance and compatibility viewpoints.

Basic knowledge, roles of other parts, and how to choose from performance and compatibility viewpoints are also explained.

≫ Related article: List of PC Parts and Explanations of Each Component [Must-Read for Custom PC Beginners]

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What Is the Role of a CPU Cooler?

A CPU cooler moves heat from the CPU efficiently to the outside and keeps the CPU at a proper temperature, preserving its intended performance.

If CPU temperature gets too high, performance drops and in the worst case it can cause failure.

Therefore, a CPU cooler is essential for stable PC operation.

When CPU temperature stays high, thermal throttling occurs and CPU performance decreases.

Thermal throttling is a safety mechanism where the CPU automatically lowers its clock speed to avoid overheating, protecting the CPU and the PC.

Lower clocks reduce processing speed, making it impossible to maintain the CPU’s original performance.

The threshold for thermal throttling depends on the product, but it generally occurs around 90°C to 105°C.

Thus, a CPU cooler with enough cooling performance is needed so that even under heavy load the CPU does not reach these temperatures.

It varies by CPU, but around 60–70°C under heavy load, and ideally no higher than about 80°C is a good target.

The necessity of CPU coolers and concrete problems from insufficient cooling are explained here:

≫ Related article: On the Necessity of CPU Coolers [Custom PC]

CPU Cooler Basics

Before choosing, review cooling methods and types as the foundation.

The following points are explained in detail.

CPU Cooler Cooling Methods

CPU cooler cooling methods are broadly divided into air cooling and liquid cooling.

An air cooler uses a metal heatsink and fan to dissipate heat from the CPU with airflow.

A liquid cooler circulates coolant to move heat efficiently and cools it at a radiator.

Furthermore, air coolers come in two types: side-flow and top-flow, and liquid coolers come in AIO (closed-loop) and custom loop.

In summary:

Air (Side-Flow / Top-Flow)

Air coolers have side-flow and top-flow designs, which differ in fan orientation and airflow direction.

Side-flow coolers mount a heatsink and fan above the CPU and push air sideways to exhaust heat.

This type offers efficient cooling performance and shines under high load, including overclocking.

Conversely, Top-flow coolers mount the fan facing downward/upward and vent heat straight up.

This design also cools nearby components and suits compact cases, though it tends to trail side-flow in cooling performance.

For mid-range and high-end CPUs, side-flow models with higher cooling performance are common.

AIO Liquid Cooling (Radiator Size)

AIO liquid coolers generally offer higher cooling performance than air coolers and are often used with high-end CPUs.

The section that receives airflow is the radiator, which comes in multiple sizes.

Radiators mount case fans, so sizes follow common fan standards.

There are two big families: 120 mm class and 140 mm class.

The 120 mm class has three sizes:

• 120 mm (one 120 mm fan)
• 240 mm (two 120 mm fans)
• 360 mm (three 120 mm fans)

The 140 mm class has three sizes:

• 140 mm (one 140 mm fan)
• 280 mm (two 140 mm fans)
• 420 mm (three 140 mm fans)

A radiator exhausts heat from the CPU using coolant; larger sizes can dissipate more heat.

Also, each PC case supports specific radiator sizes, so confirm fit before purchase.

For small cases or light workloads, 120 mm or 140 mm sizes are suitable.

For gaming, video editing, or overclocking, 240 mm or larger is preferable.

Custom Loop Liquid Cooling

(Source: Corsair iCUE Hydro X Series CX-9070008-WW)

Custom loop coolers work on the same cooling principle as AIOs, but differ greatly in assembly ease, customization, cost, and maintenance.

They are more complex and harder to assemble than AIOs, with pricier parts and required maintenance such as leak checks.

Tubes must be cut to fit the build, and care is needed to avoid leaks, so assembly and maintenance are difficult, raising the difficulty of a custom PC significantly.

Customization is high and each part can be chosen, but more knowledge and more complex assembly are required, so they are not recommended for a first-time custom PC.

≫ Related article: About CPU Cooler Cooling Methods (Air / Liquid) [Custom PC]

Types of CPU Coolers

There are two types:

• Retail coolers included with the CPU
• Aftermarket CPU coolers

Whether to use the included cooler or buy one changes the build, total cost, and cooling performance.

Retail Coolers Included with CPUs

AMD retail cooler

Some CPUs include a cooler; this included CPU cooler is called a retail or stock cooler.

It is designed by the CPU maker to maintain standard operating temperatures, and the biggest benefit is no extra cost for a cooler.

However, cooling performance is minimal and noise is often higher, so for high-load usage such as 3D gaming, creative work like video editing, or overclocking, retail coolers are not recommended.

Aftermarket CPU Coolers

Aftermarket CPU cooler
（DEEPCOOL AK620 R-AK620-BKNNMT-G）

Coolers from brands such as DEEPCOOL or COOLER MASTER are aftermarket CPU coolers made by companies other than the CPU maker.

Compared with retail coolers, choices are wider (large air, AIO liquid, etc.), and many products combine high cooling performance with low noise under load.

If a CPU does not include a cooler, or if more cooling performance is needed, an aftermarket cooler must be purchased. Check inclusion in advance.

How to Choose a CPU Cooler for a Custom PC【Performance】

This section focuses on performance and features.

Each point is explained in detail.

Based on choices in the Custom PC Tool, popularity rankings and selection rates by price/spec are summarized with statistics.

≫ Related article: Popular CPU Cooler Rankings and Selection Rates by Spec [Statistics]

Select a CPU Cooler That Matches the CPU’s TDP (Thermal Design Power)

To choose properly, first select a cooler whose cooling capacity matches the CPU’s TDP.

TDP indicates the maximum expected heat output, and the cooler should meet or exceed it.

Also consider case size, airflow, budget, and noise level.

Finding TDP can be confusing at first, so check together.

Start by finding TDP on the CPU’s product specification page.

CPU: Intel Core i5 14400F

In the spec table, refer to the Maximum Turbo Power (the highest wattage).

For Intel Core i5 14400F, it is 148 W.

CPU: AMD Ryzen 5 7600

In the spec table, refer to Default TDP/TDP.

For AMD Ryzen 5 7600, it is 65 W.

CPUs also have turbo modes that temporarily boost clock speeds beyond base to increase performance.

For Intel this is Turbo Boost Technology; for AMD it is Precision Boost.
These can exceed the listed TDP.

Overclocking can also exceed TDP.

Therefore, treat CPU TDP as a reference and choose a cooler with some headroom.

Cooler-supported TDP is often listed on official or distributor pages, though not always.

Compare CPU and cooler TDP and choose a cooler with plus-alpha margin.

That said, many coolers do not list TDP, and turbo or overclocking can exceed ratings, so judgment can be hard.

In such cases, remember these two rules of thumb:

• For mid-range CPU: “medium/large air cooler”
• For high-end CPU: “large air cooler” or “AIO liquid cooler with two or more fans”

Products vary, so not absolute, but this trend is useful.

For Mid-Range CPUs: “Medium/Large Air Cooler”

For mid-range CPU such as Intel Core i5/i7 or AMD Ryzen 5/7, medium or large air coolers are recommended.

Mid-range CPU generate less heat than high-end models, but still need proper cooling for long sessions and heavy tasks.

Medium/large air coolers use larger heatsinks and fans to move more heat.

Lower fan RPM can also reduce noise.

However, medium/large air coolers are tall, so confirm the cooler height fits the case.

Retail coolers can handle thermals, but noise can be higher under load and are not recommended for heavy use.

For everyday or office use, retail coolers may be acceptable.

If noise is bothersome after building with a retail cooler, adding an aftermarket cooler later is fine.

On the separate blog “Pasolog”, many vendor PCs were reviewed.
Photos below show what sizes vendors choose.

This Intel Core i5-14400F model uses a medium air cooler.

After reviewing about 50 systems, this size is common for mid-range CPU.

Under a heavy 3D gaming load (FF15 / FHD / High), CPU utilization averaged 50% (peaks 70–80%), and temperature averaged 60°C, so cooling was sufficient.

For High-End CPUs: “Large Air Cooler” or “AIO Liquid Cooler with 2+ Fans”

For high-end CPU such as Intel Core i7/i9 or AMD Ryzen 7/9, a large air cooler or an AIO liquid cooler with two or more fans is recommended.

High performance brings more heat, so adequate cooling capacity is important.

For AIOs, confirm the radiator size supported by the case.

This Intel Core i7-12700 model also uses a medium air cooler.

Under a similar heavy load (FF15 / FHD / High), CPU utilization averaged 20% (peaks 50%), and temperature averaged 70°C, which is within range.

However, with higher CPU load, temperatures could reach 80–90°C, which is a concern.

The Intel Core i7-12700K model uses a two-fan AIO liquid cooler.

Under the same heavy load, CPU utilization averaged 20% (peaks 50%), and temperature averaged 50°C, showing better cooling than the air cooler.

Even with heavier workloads, there should be more thermal headroom.

From these results, medium air coolers can be marginal under heavier conditions; a large air cooler or an AIO liquid cooler is preferable.

How to Choose a CPU Cooler for a Custom PC【Compatibility / Important】

This section focuses on compatibility.

Choosing an incompatible cooler can prevent assembly due to socket mismatch; always confirm.

Each point is explained in detail.

Whether a CPU Cooler Is Needed for the CPU

Some CPUs include a retail cooler; higher-performance models often require an aftermarket cooler.

How to tell inclusion of a CPU cooler can be determined from the CPU model suffix.

For Intel Core i-series, suffixes “K”, “KF”, “KS”, “XE”, “X” indicate no cooler is included.

An aftermarket cooler is required.

For AMD Ryzen, suffix “X” indicates no cooler is included, so a cooler must be purchased.

These suffix models are often high performance or overclockable, generating more heat; without proper cooling, performance can drop or, in the worst case, cause failure.

Retail cooler performance is insufficient for high-load scenarios, which is why they are not included.

Other ways include checking e-commerce listings, official specs, or even the CPU box shape.

≫ Related article: CPU Cooler Inclusion and How to Tell [Custom PC]

Motherboard Socket Support

When choosing a CPU cooler, match the motherboard’s socket type.

The socket is the CPU mounting point on the motherboard; the CPU and socket must match—and so must the cooler.

A CPU and motherboard support only one socket, but CPU coolers often support multiple socket types.

For example, a motherboard may support LGA1700 only.

A CPU cooler may list Intel LGA1700, LGA1200, LGA1151, LGA1150, LGA1155, LGA1156 and AMD AM5, AM4, etc.

Thus, if the motherboard’s socket is included in the cooler’s supported list, it is compatible.

Because many sockets are supported, cooler choices are rarely limited by socket; selection can focus on performance and design.

During assembly, a socket-specific mounting kit is included; attach it to the motherboard, then install the cooler.

≫ Related article: About CPU Cooler Socket Types [Custom PC]

Air Cooler Size (Height)

When choosing an air-cooled CPU cooler, you must ensure that its height fits within your PC case.

If the cooler is too tall, it may not fit inside the case, preventing proper assembly.

Moreover, if you select a cooler that just barely fits, it could come into contact with the case, causing vibrations throughout the chassis.

This may lead to excessive noise or even hardware damage. Therefore, it is recommended to leave at least about 1 cm of clearance.

The dimensions of each cooler are listed in the product specifications, so be sure to check them carefully.

AIO Liquid Cooler Size (Radiator Size)

For AIO liquid coolers, choose a radiator size supported by the case.

The radiator moves heat from the CPU via coolant and exhausts it; larger radiators dissipate more heat.

But large radiators may not fit, so confirm supported sizes.

Radiator families are 120 mm class and 140 mm class.

The 120 mm class has:

• 120 mm (one 120 mm fan)
• 240 mm (two 120 mm fans)
• 360 mm (three 120 mm fans)

The 140 mm class has:

• 140 mm (one 140 mm fan)
• 280 mm (two 140 mm fans)
• 420 mm (three 140 mm fans)

Depending on the model, cases often support mounting at the front, top, rear, side, or bottom.

Many support both 120 mm and 140 mm classes, enabling flexible placement.

Check for Interference Between Memory and an Air Cooler

When choosing a cooler, check for physical interference with memory.

With a large aftermarket air cooler and memory with tall heatspreaders, physical interference may prevent assembly.

Large air coolers can extend over the memory slots.

Heatsink-equipped memory is taller than standard memory and can exceed the cooler’s fin height.

These two factors can lead to interference.

The tricky part is that detailed dimensions for coolers and memory are rarely listed, making pre-purchase checks difficult.

If uncertain, using memory without tall heatspreaders is safer.

Retail coolers, AIO liquid coolers, or compact air coolers usually avoid interference even with heatsinked memory.

Summary: For Mid-Range CPUs and Above, Aftermarket Coolers Are Recommended

A CPU cooler removes heat efficiently and keeps the CPU at a proper temperature to maintain performance.

If cooling is insufficient, high-load performance drops, increasing processing time and making games feel heavy.

Therefore, choose a cooler with adequate performance for the CPU’s heat output.

Here again are the key points for choosing a CPU cooler.

The items that must not be mistaken are motherboard socket type and size.

Also check in advance whether the CPU includes a cooler.

If it is discovered later that no cooler is included, buying one fixes it, but it becomes an unexpected cost and may exceed the budget.

Basic knowledge, roles of other parts, and how to choose from performance and compatibility viewpoints are also explained.

≫ Related article: List of PC Parts and Explanations of Each Component [Must-Read for Custom PC Beginners]

あわせて読みたい

PC Parts Estimation & Compatibility Check Tool

Automatically checks each component you need when selecting parts for a custom-built PC—perfect for beginners.