Intel Core Ultra 200S · LGA1851 / Single-tower air cooler
Does the Thermalright Assassin X 120 R SE fit the Core Ultra 5 245K?
Yes. The Thermalright Assassin X 120 R SE fits the Core Ultra 5 245K with 61 W of thermal headroom; we estimate 78 °C under sustained load and 53 °C while gaming, an excellent match.
Reviewed by Farrukh Sufyan SarwarHow we estimate temperaturesPublished Prices verified Model v1.2 · data updated
Full load
78°
Gaming
53°
Idle
33°
Excellent fit
Safe at 78 °C full load
22 °C below the 100 °C junction limit under a sustained all-core load.
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The Thermalright Assassin X 120 R SE is an excellent match for the Core Ultra 5 245K, with 61 W of headroom above its 159 W boost ceiling. We estimate 53 °C in games and 78 °C under a full all-core render, leaving quiet-fan-curve room.
Thermal estimate
Both figures assume a 35 °C case-internal ambient and the cooler's sustained rating; the CPU's own junction limit caps the full-load figure.
| Load | Estimate |
|---|---|
| Idle | 33 °C |
| Gaming | 53 °C |
| Full load | 78 °C |
| Junction limit | 100 °C |
- 0–85 % comfortable
- 85–100 % fans ramp
- 100 %+ throttles
- Thermal headroom
- +61 W
- CPU boost / gaming draw
- 159 W / 90 W
- Cooler sustained rating
- 220 W
- Junction limit
- 100 °C
- Cooler height
- 155 mm
- RAM clearance
- Unrestricted
- Sockets in the box
- AM4 · AM5 · LGA1200 · LGA1700 · LGA1851
What the numbers mean for this build
- 01
61 W of sustained headroom
The Core Ultra 5 245K uses 72 % of the Thermalright Assassin X 120 R SE's rated capacity at its 159 W ceiling, which means the fans can run a relaxed curve and stay quiet even in Cinebench.
Will it physically fit?
Drag the sliders to your memory height and case limits. The schematic moves with you and shows where the Assassin X 120 R SE clashes.
This heatsink does not overhang the DIMM slots.
Listed as “CPU cooler clearance” in the case spec sheet. This cooler is 155 mm tall.
- RAM heightFits
The heatsink does not overhang the DIMM slots, so any RAM height fits.
- Cooler height vs caseFits (+10 mm)
10 mm between the cooler and the side panel.
Overall Fits for the Assassin X 120 R SE with your inputs.
Schematic, not to product scale.
Buy it, or compare the alternatives
Three tiers picked for this exact CPU: the cheapest tower that passes, the quietest liquid option per dollar, and the best low-profile heatsink.
This pairing
$17.49as of Nov 2, 05:59 AM UTC · In Stock
(opens Amazon in a new tab)ThermalrightAssassin X 120 R SE
Single-tower air cooler · 155 mm
220 W rated, 61 W headroom on the Core Ultra 5 245K.
Top air value
$29.99as of Nov 2, 05:59 AM UTC · In Stock
(opens Amazon in a new tab)ID-CoolingFROZN A620 Pro SE
Dual-tower air cooler · 157 mm
101 W of headroom; the best-value tower air cooler that passes on this CPU
Silent liquid pick
~$54
(opens Amazon in a new tab)ThermalrightFrozen Infinity 360
360 mm AIO liquid cooler · 52 mm
Estimated 63 °C under full load with quiet fan curves
Small-form-factor pick
$27.99as of Nov 2, 05:59 AM UTC · In Stock
(opens Amazon in a new tab)ThermalrightAXP120-X67
Low-profile air cooler · 67 mm
67 mm tall and still 99 °C at full load
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply to the purchase of this product.
Related reports
Other coolers on the Core Ultra 5 245K
- Thermalright Peerless Assassin 120 SEExcellent fit
- Thermalright Phantom Spirit 120 SEExcellent fit
- Noctua NH-D15Excellent fit
- Noctua NH-D15 G2Excellent fit
- Noctua NH-D12LExcellent fit
- be quiet! Dark Rock Pro 5Excellent fit
- Lian Li Galahad II Trinity 240Excellent fit
- Corsair Nautilus 360 RSExcellent fit
- Thermalright Burst Assassin 120Excellent fit
- Cooler Master Hyper 212 Halo BlackAcceptable fit
Thermalright Assassin X 120 R SE on other CPUs
Terms used on this page
- Thermal headroom
- The cooler's sustained dissipation rating minus the CPU's boost power limit, in watts. Positive headroom lets fans run slower and quieter; 25 W or more is rated Excellent here.
- TjMax
- The maximum junction temperature the maker allows, typically 95–100 °C. AMD lists 90 °C for the Ryzen 7 5800X3D, 89 °C for the 7800X3D and 95 °C for the 9800X3D. At TjMax the CPU throttles clocks to stay in place; it will not overheat, but it will lose performance.
- PL1 / PL2
- Intel's two power limits. PL1 (Processor Base Power) is the sustained draw the CPU settles at; PL2 (Maximum Turbo Power) is the short-term boost ceiling. Many desktop boards run PL2 indefinitely, so a cooler must be sized for PL2, not PL1.
- Thermal throttling
- Automatic clock reduction when the CPU hits TjMax. A pairing is flagged as a throttling risk when the modelled full-load temperature reaches the junction limit or the cooler is rated 15 W or more below the CPU's boost power.
- RAM clearance
- The tallest memory module that fits under an air cooler's front fan in its stock position. Dual-tower coolers with less than 42 mm clash with tall RGB kits (typically 44 mm) unless the fan is raised.
- CPU cooler height
- The installed height of an air cooler from the motherboard, compared against the case's published CPU cooler clearance. Coolers at or above 160 mm exclude many compact Micro-ATX and tempered-glass mid-towers.
Frequently asked questions
Will the Thermalright Assassin X 120 R SE keep the Core Ultra 5 245K from thermal throttling?
Yes. The estimated full-load temperature is 78 °C, 22 °C below the 100 °C throttle point.
What temperature should I expect while gaming on the Core Ultra 5 245K with this cooler?
Around 53 °C with a 35 °C case ambient, because GPU-bound games only draw about 90 W from the CPU package. Cooler rooms and better case airflow lower that figure.
Does the Thermalright Assassin X 120 R SE fit tall RGB RAM?
Yes. The heatsink does not overhang the memory slots, so any module height works.
Is the Thermalright Assassin X 120 R SE compatible with the LGA1851 socket?
Yes, LGA1851 hardware is included. Supported sockets: AM4, AM5, LGA1200, LGA1700, LGA1851.
Hubs: Core Ultra 5 245K · Thermalright Assassin X 120 R SE · LGA1851