Calculating cooling requirements...
Select a CPU and GPU above, then click Check Cooling →
Or load a preset to see an example build instantly
Why Rated TDP Is Misleading — Intel PL1 vs MTP
Intel's "TDP" figure (formally PL1) is the long-term sustained power limit — a conservative number designed for system integrators. Under normal all-core boost (MTP, formerly PL2), Intel CPUs draw dramatically more power. A 240mm AIO sized for 125W (TDP) on an i9-14900K will throttle within seconds because the chip actually pulls 253W.
| CPU | Rated TDP (PL1) | Real Max Draw (MTP) | Gap | Min Cooler |
|---|---|---|---|---|
| Core i9-14900K | 125W | 253W | +103% | 360mm AIO |
| Core i7-14700K | 125W | 253W | +103% | 360mm AIO |
| Core Ultra 9 285K | 125W | 250W | +100% | 360mm AIO |
| Core i5-14600K | 125W | 181W | +45% | 240mm AIO |
| Ryzen 9 9950X | 170W | 200W | +18% | 360mm AIO |
AMD is more transparent — Ryzen TDP (PPT) values are closer to real all-core draw, though "eco mode" can cut consumption significantly. This calculator uses real sustained power values for both brands to give you an accurate cooler requirement.
Air Cooler vs AIO: When to Use Each
The choice between air and AIO is not just about TDP — it also involves noise, reliability, form factor, and aesthetics. Here is the honest decision matrix:
| Cooler Type | Best for | TDP Range | Noise | Lifespan |
|---|---|---|---|---|
| Budget Air | Mid-range non-K Intel, Ryzen 5 | ≤95W | Low–Medium | 10–15+ yrs |
| High-End Air (NH-D15) | Ryzen 7/9, silent builds up to 200W | ≤200W | Very Low | 10–15+ yrs |
| 240mm AIO | Mid-range Intel K chips, ITX builds | ≤230W | Low–Medium | 5–7 yrs |
| 360mm AIO | High-end Intel K, Ryzen 9 OC | ≤340W | Low | 5–7 yrs |
| Custom Loop | Extreme OC, multi-component cooling | Unlimited | Very Low | 15+ yrs (with maintenance) |
AIOs have a pump that can fail — typically after 5–8 years. for a silent, long-term build under 200W, the Noctua NH-D15 or be quiet! Dark Rock Pro 5 outperform most AIOs while lasting indefinitely and requiring no maintenance.
What 775W of System Heat Actually Means
An RTX 5090 (575W) paired with a Ryzen 9 9950X (200W real power) produces approximately 775W of heat — comparable to a small space heater. Running this build for eight hours produces over 6 kWh of heat that your cooling system must actively exhaust. Here is what this build specifically requires:
CPU Cooler
360mm AIO minimum
Arctic Liquid Freezer III 360, Corsair H170i
Case
Extreme airflow mandatory
Lian Li O11 XL, Phanteks Enthoo Pro II
PSU
1000W+ ATX 3.0
Must have 12V-2×6 connector for RTX 5090
Case Fans
4+ 120mm or 140mm fans
Push-pull on radiator + 2 exhaust minimum
ITX and mATX Thermal Constraints
Small form factor builds are thermally punishing. Most ITX cases cap cooler height at 65–70mm — this rules out both dual-tower air coolers and 280/360mm AIOs. The GPU's hot air recirculates inside the smaller case, raising ambient by 5–10°C. This calculator adds a 25% penalty to cooling requirements for ITX builds to account for these constraints.
If you're building ITX with a CPU drawing more than 140W, a purpose-designed SFF case is essential: the SSUPD Meshlicious, Fractal Terra, or DAN A4 are engineered specifically for high-TDP components in tight spaces.
Frequently Asked Questions
Is a 240mm AIO enough for a Core i9-14900K?
No — not at stock Intel power limits. The i9-14900K draws up to 253W (MTP), which exceeds the 200–230W ceiling of most 240mm AIOs. You will see immediate thermal throttling at full all-core load. A 360mm AIO (Arctic Liquid Freezer III 360, Corsair H170i) or the Noctua NH-D15 are the minimum safe options. Alternatively, enable Intel's 125W power limit in BIOS (PL1=PL2=125W), which reduces boost duration but keeps temperatures manageable on a 240mm AIO.
Does GPU heat affect CPU temperatures?
Indirectly yes. The GPU raises case ambient temperature by 5–15°C under full load, and your CPU cooler works against that ambient. Use the Ambient field to model a warm-case scenario (set 30–35°C if you have a hot GPU in a mid-tower). In high-airflow cases (Fractal Torrent, Lian Li O11), GPU heat exhausts more efficiently, keeping ambient closer to room temperature.
Do I need thermal paste, or is the included paste fine?
Included paste on quality coolers (Noctua, Arctic) is excellent and pre-applied optimally. Aftermarket paste (Thermal Grizzly Kryonaut, Noctua NT-H2, Arctic MX-6) offers 2–5°C improvement — meaningful only when operating near thermal limits. for extreme builds (253W Intel K CPUs, heavily overclocked Ryzen), the marginal gain from premium paste is worth the $10–15 cost.
Can undervolting reduce my cooling requirements?
Yes, significantly. Undervolting (reducing CPU core voltage while maintaining the same clock speeds) can cut power consumption by 20–40W with no performance loss. An i9-14900K that draws 253W stock may draw 190W undervolted — dropping the cooler requirement from a 360mm AIO to a 240mm AIO. Use the Manual W override to model your undervolted power draw. Intel's E-core disable strategy (in BIOS) also reduces MTP substantially on 12th–14th gen.
What PSU do I need for an RTX 5090 build?
The RTX 5090 requires an ATX 3.0 PSU with a native 12V-2×6 connector rated for 600W+ transient spikes. NVIDIA recommends a 1000W PSU minimum for the RTX 5090 alone. Paired with a high-TDP CPU (9950X, 14900K), a 1200W PSU is advised. Use our PSU Wattage Calculator for a full component-by-component breakdown including drives, RAM, and fan overhead.
Is a Noctua NH-D15 better than a 240mm AIO?
In most scenarios at ≤180W, yes. The NH-D15 handles up to 200W with lower fan noise, no pump to fail, and a 10+ year lifespan vs 5–7 years for an AIO. The 240mm AIO wins in ITX builds (where the NH-D15 is too tall), in cases with poor CPU clearance, or when you need the RAM clearance that a tower cooler blocks. for CPUs above 200W (i9-14900K, Core Ultra 9 285K), a 360mm AIO is required and outperforms the NH-D15 at load.
Related Tools
PSU Wattage Calculator
Component-by-component power draw for any build configuration.
CPU & GPU Bottleneck Calculator
Check if your CPU is limiting your GPU's performance at your target resolution.
GPU Price-to-Performance
Rank any GPU by performance per dollar — RTX 5080 vs RX 9070 XT.
PC Build Budget Planner
Get the ideal GPU/CPU/RAM/storage split for your total build budget.
GPU FPS Estimator
Estimate FPS for 45 GPUs across 35+ games at 1080p, 1440p, and 4K.
PC Upgrade Cost & ROI
Calculate the true net cost and performance gain of any GPU or CPU upgrade.