TweakGearPro
Cooling & Case DIYNo signupNo paywallInstant resultsUpdated 2026-08-02

Case Airflow Layout Simulator

Visualize positive vs negative pressure and fix dust buildup and dead air.

Local & private by design

All processing runs locally in your browser, no data uploaded to servers. Nothing you enter leaves this page — there is no backend, no tracking pixel, no third-party API call. Close the tab and the inputs are gone.
← All toolsHow it works ↓
Intake
110 CFM
Exhaust
55 CFM
Net
+55
Pressure & dust
Strongly positive
Dust risk: Low
Good base flow. Add a front-low intake if GPU temps are high.

The clean case that filled with dust

"My case has dust on every interior surface even though I have fan filters." The likely cause is negative pressure — more exhaust CFM than intake CFM — which pulls unfiltered air in through every gap, crack, and unused vent. Filters only work when air enters through them, which only happens when intake CFM exceeds exhaust. A balanced or slightly positive pressure keeps dust out and cooling efficient.

The Case Airflow Layout Simulator takes your intake and exhaust fan counts, sizes, and RPMs, computes the pressure balance, and flags dust, cooling, and dead-air risks. Plan a clean, cool layout before you mount a single fan. Runs locally, no signup.

How the tool works

The simulator computes three things:

  • Pressure balance — slightly positive (more intake CFM than exhaust), balanced, or negative. Slightly positive keeps dust out through filters; strongly negative pulls dust in through every gap.
  • Intake/exhaust ratio — the CFM ratio between intake and exhaust fans. Ideal is ~1.1–1.3 (slightly positive). Below 1.0 is negative; above 1.5 is over-pressured (wastes fan capacity).
  • Dust and temp verdict — flags dust buildup risk (negative pressure), dead-air pockets (insufficient intake in the GPU zone), and temp risks (insufficient exhaust).

The tool also recommends fan placement — front and bottom intake, rear and top exhaust — and flags the common dead-air pocket in front of a hot GPU.

Step-by-step usage

  1. Enter your intake fans — count, size (120mm / 140mm), and approximate RPM.
  2. Enter your exhaust fans — count, size, RPM.
  3. Note any obstructions — front-mounted radiator, dust filters (which reduce CFM by 10–30%), drive cages blocking intake.
  4. Read the pressure verdict. Slightly positive is the target.
  5. Adjust fan placement or RPM to hit a 1.1–1.3 intake/exhaust ratio.

Common hardware problems this tool solves

  • "Dust on every interior surface" — negative pressure. Increase intake CFM or decrease exhaust CFM. Filters only work when air enters through them.
  • "My GPU runs hot despite good case fans" — the GPU may sit in a dead-air pocket. Add a front intake low, or a bottom intake, to feed it fresh air.
  • "My CPU runs hot but the case feels cool" — the CPU cooler may be suffocated by a front radiator or by exhaust fans fighting the CPU cooler. Check the layout.
  • "My fans are loud but temps don't improve" — likely a layout problem, not a fan-count problem. Two well-placed fans beat six poorly placed ones.

For deeper cooling context, browse the CPU fix hub and the Fan Curve Simulator.

Pro tips for case airflow

  • Slightly positive pressure keeps dust out. More intake CFM than exhaust forces air out through gaps, so dust cannot enter except through filtered intakes.
  • 2 intake + 1 exhaust handles most builds. Adding fans beyond 4–5 gives diminishing returns unless you fix the layout first.
  • Filters belong on intakes only. Filters on exhausts only choke airflow and collect nothing useful.
  • Front-mounted radiators eat GPU clearance and warm the GPU. The radiator pre-warms intake air, raising GPU temps by 5–10°C. Top-mount the radiator if your case allows.
  • Feed the GPU fresh air. Many hot-GPU problems are dead-air problems. A bottom intake or a low front intake aimed at the GPU can drop temps by 5–8°C.

Airflow is layout, not fan count. The simulator exists so you plan a clean, cool layout instead of bolting on fans until temps improve.

Case Airflow Layout Simulator — FAQ

Positive or negative case pressure?▾
Slightly positive (more intake CFM than exhaust) keeps dust out through filters. Strongly negative pulls dust in through every gap.
How many fans do I need?▾
Usually 2 intake + 1 exhaust handles most builds. Adding fans beyond 4–5 gives diminishing returns unless you fix the layout first.
Why are my GPU temps high with good case fans?▾
The GPU may sit in a dead-air pocket. Add a front intake low, or a bottom intake, to feed it fresh air.
Should I use fan filters everywhere?▾
On intakes, yes. On exhausts, no — filters there only choke airflow and collect nothing useful.
Are these hardware tools free to use?▾
Yes — every tool on TweakGearPro is 100% free, requires no account, and runs entirely in your browser. Nothing is uploaded to a server.
Do these tools work offline or send my data anywhere?▾
All processing runs locally in your browser, no data uploaded to servers. Once the page loads, the calculator works without a network connection.
Can I print or save my results?▾
Yes. Each tool has a "Print results" button that opens your browser print dialog, where you can save to PDF. Print styling hides navigation and side panels automatically.
Are the estimates accurate for my specific hardware?▾
They model typical real-world scaling across tiers, not any single SKU. Treat results as a planning baseline and always cross-check critical decisions against vendor specs and your own benchmarks.
Do the tools work on mobile?▾
Yes. Every tool stacks vertically on phones with touch-friendly inputs. Complex tables stay readable and scroll horizontally when needed.

Cross-site hardware resources

GameFixPro — Game FPS & Hardware TuningGame-side frame-rate fixes and hardware适配 guides.DevFixPro — Driver & System Error RepairDriver crash, BSOD and system error troubleshooting.