Datasheet figures next to each other, and the airflow balance, pressure verdict and case air heating that the fans in each box compute to behind that case's own front. Calculated with the CaseFlow model, not measured.
| BitFenix Colossus Micro-ATX | Fractal Design Define 7 Nano | |
|---|---|---|
| Form | Micro-ATX mid tower | Mini ITX |
| Volume | 30.9 L | 29.5 L |
| Dimensions | 250 × 330 × 374 mm | 399 × 205 × 361 mm |
| Front | solid solid or glass front | solid solid or glass front |
| Fan mounts | front 1 × 120, top 2 × 120, rear 1 × 120, bottom 2 × 120 | front 2 × 120/140, top 2 × 120/140, rear 1 × 120, bottom 1 × 120 |
| Radiator support | front 120 mm, top 240 mm, rear 120 mm, bottom 230 mm | front 280 mm, rear 120 mm |
| Dust filters | front, bottom | front, top, bottom, psu |
| GPU length | 320 mm | 331 mm |
| Cooler height | 160 mm | 167 mm |
| Stock fans | 1 × stock fan (bottom) | 1 × Dynamic X2 GP-14 (front), 1 × Dynamic X2 GP-12 (rear) |
| Stock airflow, max rpm | – | 34 in / 0 out CFM |
| Stock pressure verdict | stock fans named but no datasheet - nothing computed | positive, worst case included |
| Case air at 290 W | – | +15.5 K |
| Stock fan noise | – | 19.1 dB(A) |
| All mounts, reference fans | 121 in / 158 out CFM 3 / 3 mounts | 130 in / 185 out CFM 3 / 3 mounts |
With a reference pressure-optimized fan on every mount the Define 7 Nano moves more air. The stock fans of the Colossus Micro-ATX are named without figures behind them, so its stock columns stay empty. The pressure verdict describes the stock fan set, not the case: stronger or extra intake fans in the free mounts, or slower exhaust fans, turn a negative balance positive.
Each stock fan contributes CFMmax · derate · rpm/rpmmax behind its wall's mounting class: filtered mesh
front and side mounts as dust filter, bottom as floor + filter, top and rear as open grille, solid and glass fronts as side-slit intake at
roughly half of a mesh front. Front, bottom and side blow in; top and rear blow out.
| Mounting | Airflow blades | Pressure-optimized |
|---|---|---|
| Open grille | 0.88 (0.80–0.95) | 0.88 (0.80–0.95) |
| Dust filter | 0.70 (0.60–0.80) | 0.78 (0.70–0.86) |
| Floor + filter | 0.64 (0.52–0.74) | 0.72 (0.62–0.80) |
| Solid or glass front | 0.50 (0.40–0.62) | 0.58 (0.48–0.68) |
Worst case sums intake at the low end of each band and exhaust at the high end; positive there means positive regardless of how the estimates fall. Case air: ΔT = 3.1 · W / throughput (m³/h), with an open-cooler GPU putting its full board power into the case air plus board, RAM and drives. Capacity puts a reference pressure-optimized fan on every mount at max rpm — 120 mm 60 CFM, 140 mm 75 CFM — a generic good fan, not a product.
Mount counts, radiator support and clearances are datasheet figures. Nothing here is measured; the same model runs in CaseFlow.