CPU Cooler Check · thermal fit calculator

Will that cooler
actually keep your
CPU cool?

Free CPU cooler calculator and compatibility checker for 120 CPUs and 70 coolers

Spec sheets say “supported”. They don’t say a 253 W Core i9 will sit at 100 °C on a 120 mm tower. Pick a processor and a cooler to get estimated gaming and full-load temperatures, headroom in watts, RAM clearance and case height, all from published power limits.

Processors: 120
Coolers: 70
Pairings: 8400

On the bench

Fit check instrument

Processor

Cooler

Choose both parts. The verdict is computed instantly from the CPU’s boost power limit and the cooler’s sustained rating.

How to check CPU cooler compatibility

The calculator above runs four checks on every CPU and cooler pair. You can run them by hand with a spec sheet; a cooler has to pass all four. Read how to check CPU cooler compatibility for each check in detail.

Common starting points: Best cooler for 5800X3D, Best cooler for Ryzen 5 5600, 9800X3D cooler picks.

Check 1
Socket match
A cooler only fits if its box includes mounting hardware for your CPU's socket: AM5, AM4, LGA1851, LGA1700 or LGA1200. The socket is set by your motherboard, so this is the motherboard compatibility check. AM5 keeps the AM4 hole pattern and LGA1851 keeps LGA1700's, so many kits carry over, but confirm the socket list before you buy.
Every cooler's socket list
Check 2
Power vs sustained rating
Compare the CPU's boost power limit (Intel PL2, AMD PPT), not its TDP, with the cooler's sustained dissipation rating. Thermal headroom is the difference in watts: 25 W or more is Excellent and anything less is Acceptable. A cooler more than 15 W short, or one whose full-load estimate reaches the CPU's junction limit, is a throttling risk.
Boost power for 120 CPUs
Check 3
RAM clearance
Large air coolers overhang the memory slots, so each one has a maximum RAM height it clears with the front fan in place. Standard heatspreaders are about 38 mm and tall RGB kits about 44 mm; dual-tower coolers that clear less than 42 mm are flagged for tall kits. Liquid coolers have no RAM limit.
Clearance rules and formula
Check 4
Case height and radiator space
An air cooler must be shorter than the case's maximum CPU cooler height; at 160 mm and above, many compact Micro-ATX cases are ruled out. A liquid cooler instead needs a radiator mount of its length (240, 280, 360 or 420 mm) in the top or front of the case, with room for the radiator and fans.
Heights and radiators, ranked for AM5
Water cooler? Check will a water cooler fit my PC.

Questions people ask

How do I check if a CPU cooler is compatible with my motherboard?

Check the socket. Your motherboard's CPU socket, for example AM5 or LGA1700, must appear in the cooler's list of included mounting kits. Then confirm the cooler clears your RAM and fits inside your case; the calculator on this page runs all four checks for any CPU and cooler pair.

How do I check CPU cooler compatibility?

Run four checks: socket support, thermal headroom (the cooler's sustained rating minus the CPU's boost power limit), RAM clearance, and case height or radiator space. Pick a CPU and a cooler in the calculator above to get all four at once.

What happens if my cooler is too weak for my CPU?

The CPU heats up to its junction limit (TjMax) and then lowers its clock speed to stay there, which is thermal throttling. Games often still run normally because they draw far less than the boost limit, but long renders, compiles and benchmarks run slower and the fans run at full speed.

How much RAM clearance does a CPU cooler need?

As much as your memory is tall: about 32 mm for bare modules, 38 mm for standard heatspreaders and 44 mm or more for tall RGB kits. Check the cooler's RAM clearance figure; many dual-tower coolers let you raise the front fan for taller kits, at the cost of total height.

Will a 360mm AIO fit my case?

Only if the case lists a 360 mm radiator mount, usually in the top or front, with enough depth for the radiator plus fans (about 52 mm together) and no clash with tall memory or motherboard heatsinks when top-mounted. Each case page here lists the largest radiator it takes at each position.

The model, in one line

Full-load estimate

T = 35 °C + 253 W boost limit ÷ 390 W cooler rating × 60

The Core i9-14900K on the Arctic Liquid Freezer III Pro 420 A-RGB works out to 74 °C. Anything that lands on the CPU’s junction limit is flagged as a throttling risk, and a cooler rated 15 W or more under the boost ceiling fails outright. Gaming uses the CPU’s typical in-game draw instead of its ceiling.

Arctic Liquid Freezer III Pro 420 A-RGBrated 390 W

Physical checks

42 mmDual towers under this RAM clearance clash with tall RGB kits.
160 mmAir coolers at or above this height miss many compact Micro-ATX cases.
220 WIntel PL2 above this on a 120 / 240 mm cooler triggers a sustained-draw warning.