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 | Thermaltake 420 EX Pro | |
|---|---|---|
| Radiator | 420 mm | 420 mm |
| Core thickness | 30 mm | 27 mm |
| Stock fans | 3 × Aurora Rise Fan | 3 × TOUGHFAN EX14 Pro |
| Fan rpm, datasheet | ? – 2000 | 500 – 2000 |
| Pump | 2600 rpm max | 3300 rpm max |
| Tubing | 400 mm | 460 mm |
| Dissipation at max rpm | 39.8 W/K | 43.9 W/K |
| Coolant, 250 W, 30 °C intake | 36.3 °C | 35.7 °C |
| Noise at max rpm, all fans | – | 36.4 dB(A) |
No noise rating for one of the stock fans in the data.
| K above intake | Eisbaer Pro Aurora rpm | dB(A) | 420 EX Pro rpm | dB(A) | Quieter |
|---|---|---|---|---|---|
| 10.0 | 921 | – | 782 | 17.1 | |
| 12.5 | 635 | – | 539 | <15 | |
| 15.0 | 469 | – | 500 min | <15 | |
| 17.5 | 362 | – | 500 min | <15 | |
| 20.0 | 290 | – | 500 min | <15 | |
| 25.0 | 200 | – | 500 min | <15 |
The 420 EX Pro dissipates 43.9 W/K against 39.8 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.