Both coolers at the same heat load: what each dissipates, the coolant temperature over fan speed, and the fan speed and noise each needs for the same temperature. Calculated from radiator size, core thickness and the stock fans' datasheets, not measured.
| Alphacool Eisbaer Pro Aurora 240 | NZXT Kraken 240 (2023) | |
|---|---|---|
| Radiator | 240 mm | 240 mm |
| Core thickness | 30 mm | 30 mm |
| Stock fans | 2 × Aurora Rise Fan | 2 × F120P (Kraken 2023 stock) |
| Fan rpm, datasheet | ? – 2000 | 500 – 2200 |
| Pump | 2600 rpm max | 2800 rpm max |
| Tubing | 400 mm | 400 mm |
| Dissipation at max rpm | 22.7 W/K | 20.1 W/K |
| Coolant, 250 W, 30 °C intake | 41.0 °C | 42.5 °C |
| Noise at max rpm, all fans | – | 33.0 dB(A) |
No noise rating for one of the stock fans in the data.
| K above intake | Eisbaer Pro Aurora 240 rpm | dB(A) | Kraken 240 (2023) rpm | dB(A) | Quieter |
|---|---|---|---|---|---|
| 10.0 | not reachable | – | not reachable | – | |
| 12.5 | 1614 | – | 2190 | 32.9 | |
| 15.0 | 1191 | – | 1616 | 26.4 | |
| 17.5 | 921 | – | 1250 | 21.0 | |
| 20.0 | 737 | – | 1001 | 16.7 | |
| 25.0 | 508 | – | 690 | <15 |
The Eisbaer Pro Aurora 240 dissipates 22.7 W/K against 20.1 W/K at max fan rpm. No noise rating for one of the stock fans in the data yet, so temperature only. A cooler pinned at its fan's minimum rpm runs colder than the row asks; the comparison is then not at equal temperature.
A radiator moves heat in proportion to the difference between coolant and incoming air: Q = q · (Tcoolant − Tair).
q depends on the air actually passing through the core. Airflow per fan is CFMmax · derate · rpm/rpmmax
with the radiator derate (0.62, or 0.72 for pressure-optimized blades) times the core-thickness factor. Per 120 mm segment at 27 mm:
q = 8.5 W/K · (airflow / 45 CFM)0.6; heat transfer over fins scales with roughly the 0.6 power of velocity.
| Core | Airflow factor | Fin area factor |
|---|---|---|
| 27 mm | 1.00 | 1.00 |
| 30 mm | 0.97 | 1.09 |
| 38 mm | 0.90 | 1.15 |
| 45 mm | 0.84 | 1.22 |
Thick cores gain fin area but lose airflow; at low rpm the net is close to zero. With fans off, natural convection is taken as 1 W/K per segment.
The band is ±15 % on q: fin density, coolant flow and preheated case air. Pump speed matters little above roughly 1 l/min.
Noise is the stock fan's curve plus 10 · log₁₀(fan count).
Air entering the radiator is case air, usually 5 to 10 K above room. Die temperatures sit above the coolant by the block and TIM delta, typically 25 to 45 K under load. Nothing here is measured; the same model runs in RadiatorTemp.