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PC Airflow Simulator With Real Physics and Temperatures

PC Airflow Simulator lets you set up your own fans, graphics card and CPU cooler in a 3D computer case.

Real airflow physics then shows where the air goes and how warm it gets.

Parts starved of fresh air stand out, so you know what to fix.

Load the model to see air move through the case in 3D.

How the PC Airflow Simulation Works

  • Real spinning blades Each fan is simulated as spinning blades that push on the air. They are tuned so one fan alone matches its maker's data, such as ARCTIC's P12 fan curve.
  • Parts that slow the air Heatsink fins, radiators, dust filters, and the case's steel mesh all resist the air. So a fan moves less in a case than its box says, as the Noctua airflow guide explains. How much each one holds back is based on published lab tests of similar parts, such as these perforated plate measurements.
  • Air solved in 3D Standard detail splits the case and the air around it into about 170,000 cells, each 1 cm wide. The flow is worked out in every cell, even in the gaps between parts.
  • Heat that moves with the air In Pro, your graphics card and CPU warm the air flowing through them. The model carries that warm air through the case as it rises, so you see which parts end up breathing it in. Each chip's temperature then comes from lab tests of that part, plus the air it gets.

PC Case Airflow Tier List

We simulated every case with the same kind of fans, graphics card, and CPU cooler. Its airflow score is how much of its intake fans' open-air flow gets into the case.

S 80%+

No case tested so far

A 65 to 79%

  • Lian Li O11 Dynamic EVO

    Mid-tower

    68% airflow score

    Test details
    Intake fans
    3 × 120 mm, side
    Their open-air flow
    132 CFM
    Air in through them
    91 to 99 CFM
    Graphics card air
    37 CFM
    CPU cooler air
    34 CFM
    Case pressure
    Positive

  • Lian Li Vector V100

    Mid-tower

    65% airflow score

    Test details
    Intake fans
    3 × 120 mm, side
    Their open-air flow
    132 CFM
    Air in through them
    87 to 92 CFM
    Graphics card air
    36 CFM
    CPU cooler air
    34 CFM
    Case pressure
    Positive

    Its side fans draw through the mesh side panel. The link goes to the V100R, the same case with three side fans and a rear fan included.

  • NZXT H5 Flow (2024)

    Mid-tower

    77% airflow score

    Test details
    Intake fans
    3 × 120 mm, front
    Their open-air flow
    132 CFM
    Air in through them
    103 CFM
    Graphics card air
    38 CFM
    CPU cooler air
    36 CFM
    Case pressure
    Positive

B 50 to 64%

  • Corsair 4000D Airflow

    Mid-tower

    54% airflow score

    Tip: Its fine front dust filter comes fitted and holds back about 24% of the intake air. Take it out and the case scores 72%, which is A tier.

    Test details
    Intake fans
    3 × 120 mm, front
    Their open-air flow
    132 CFM
    Air in through them
    73 to 74 CFM
    Graphics card air
    39 CFM
    CPU cooler air
    37 CFM
    Case pressure
    Positive

    With the filter out, 96 to 98 CFM came in.

  • Fractal Design North (Mesh)

    Mid-tower

    59% airflow score

    Tip: Its front dust filter comes fitted and holds back about 26% of the intake air. Take it out and the case scores 79%, which is A tier.

    Test details
    Intake fans
    2 × 140 mm, front
    Their open-air flow
    142 CFM
    Air in through them
    85 to 86 CFM
    Extra air in through vents
    5 CFM
    Graphics card air
    36 CFM
    CPU cooler air
    34 CFM
    Case pressure
    Neutral

    Its front takes two 140 mm fans. The mesh side panel lets in extra air without a fan. With the filter out, 114 to 116 CFM came in.

C Under 50%

  • Cooler Master MasterBox Q300L

    Micro-ATX

    29% airflow score

    Tip: Its magnetic front, top and bottom dust filters come fitted and hold back about 6% of the intake air. Take them out and the case scores 30%, which is C tier.

    Test details
    Intake fans
    2 × 120 mm, front
    Their open-air flow
    88 CFM
    Air in through them
    26 CFM
    Extra air in through vents
    8 CFM
    Graphics card air
    32 CFM
    CPU cooler air
    34 CFM
    Case pressure
    Negative

    Its front takes two 120 mm fans. The front, top and floor are steel with small round holes, only about 21% open. With the filters out, 27 CFM came in.

  • Cooler Master NR200P

    Mini-ITX

    41% airflow score

    Tip: Its bottom and side dust filters come fitted and hold back about 18% of the intake air. Take them out and the case scores 52%, which is B tier.

    Test details
    Intake fans
    2 × 120 mm, bottom
    Their open-air flow
    88 CFM
    Air in through them
    37 to 40 CFM
    Extra air in through vents
    27 CFM
    Graphics card air
    24 CFM
    CPU cooler air
    29 CFM
    Case pressure
    Negative

    Its rear only takes a 92 mm fan, so both exhausts sit in the top. With the filters out, 46 to 49 CFM came in.

How we test

Intake fans fill each case's main intake panel, with three 120 mm fans where it takes them. Two exhausts go on the rear and top-rear mounts, or the top-front when the rear can't take one. Every fan is a generic model in its mount's size at 1,200 RPM.

Every case also holds the same graphics card and CPU cooler, with its dust filters as shipped. We set these rules before testing each new case.

The intake fans would move a set amount of air with nothing in their way, such as 132 CFM for three 120 mm fans. The airflow score is the share of that air they pull into the case. We run each case at the Detailed and Standard settings and use the lower score.

The tier cutoffs were set before any case was scored. Within a tier, cases are listed A to Z.

Graphics card and CPU cooler air doesn't set the tier, so each card shows it in its details. It changed little between the mid-towers, while the Mini-ITX NR200P gave both parts the least air.

We call case pressure neutral when it's within 0.25 Pa of the room. When we checked our model against a much bigger simulated room, its pressure readings stayed that close, so anything nearer zero is too close to call.

These are simulated results, not hands-on tests, and accuracy against a real case is not validated. To check one yourself, pick the case in the simulator above and set up the same fans.

PC Airflow Simulator Pro

It comes with Computer Info Bits Pro, along with our Windows apps and every other Pro tool, on one license key.

Computer Info Bits Pro

PC Airflow Simulator Pro and every other Pro feature, on our site and in our Windows apps.

$10 per month

Billed every month. Cancel anytime.

$60 per year

Billed once a year. The same as 6 months.

Subscribe for US$10 a month
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Prices are in US dollars, plus sales tax where it applies. Cancel anytime. You keep access until the end of the period you've paid for. Payments are not refunded for unused time. Your receipt and license key arrive by email.

See everything the simulator adds

Check Your PC's Airflow Without Opening the Case

Is your case in the tier list above? Its score is a quick read on how well that case breathes with a common fan setup.

Next, find which way each of your fans blows. On Noctua fans, air leaves the side with the round hub sticker. With the PC on, a thin strip of tissue held outside a vent gets pulled in at an intake and pushed away at an exhaust.

Then build your fan layout in the simulator and run it with Pro. If little air reaches your graphics card or CPU cooler, or the air it gets runs warm, you've found the weak spot before you pick up a screwdriver.

Set Up a Fan Configuration and Run a PC Case Airflow Simulation

  1. Pick a fan layout, or keep the default one.
  2. Select a fan to change its position, direction, model, and speed.
  3. With Pro, pick your Graphics card, CPU and Load under Heat from parts, or a heat level such as Gaming, and set your Room temperature.
  4. Select Run airflow and wait for the result.

The simulation runs on your computer. Browsers that support WebGPU use the graphics card and finish much faster. Temperatures need WebGPU, so other browsers show airflow only.

Read the Airflow Visualization

Moving streaks
Each streak points the way the air moves. In air speed colors, deep blue is slow air and pale cyan is fast air, not colder air.
Air temperature colors (Pro)
After a heated run, the streaks show how warm the air is. Blue is room air, amber is warm, and red is 20 °C (36 °F) or more above the room. A switch on the legend swaps back to air speed.
Fan rings
Blue marks an intake fan and orange marks an exhaust fan.
Case pressure
Positive means more air comes in than goes out, so the extra leaves through gaps and helps keep dust out.
Graphics card and cooler air
How much air reaches the parts that make the most heat.
Chip temperatures (Pro)
How hot your graphics card and CPU get, for the parts you pick, each with a range. Compare two layouts to see if a change cools them, or if they come out about the same.
Air temperatures (Pro)
How warm the air is going into the graphics card and CPU cooler, leaving the case, and on average inside it. Each one shows the air's own temperature in the room you set, with its rise above the room.

Use the Result as a Comparison

The model simplifies cables, small gaps, and grilles. Use it to compare layouts, one change at a time, then check the real PC under the same load.

How Close the Temperatures Are

We checked the air temperatures against OpenFOAM, a separate airflow program engineers use, and the overall warming agreed closely. The air going into the graphics card and CPU cooler came within a few degrees.

So those two can be off by about ±4 °C (±7 °F), and the air leaving the case and the case average by about ±10%.

Chip temperatures start from lab tests of real parts, such as TechPowerUp's reviews, and add the air your layout sends to each part. Two cards of the same model can run several degrees apart, so chip temperatures can be off by about ±10 °C (±18 °F). A change between two layouts of the same PC is closer than that, because the parts are the same in both.

We're setting up tests in a real PC to make all of these more accurate.

Guides From Our Tests

PC airflow optimization guide
Fan direction, common layouts and repeatable testing.
Rear top fan test
How flipping one fan's direction changes the result.
Lian Li O11 fan guide
Layouts compared in our O11 Dynamic EVO model.
Corsair 4000D Airflow guide
What each added fan changed in that case.
NZXT H5 Flow guide
Four layouts, including two intakes under the graphics card.
4000D Airflow vs H5 Flow
The same parts and fans in both cases, temperatures included.
4000D Airflow vs Fractal North
What the North's side fans did against a 4000D Airflow.
Fractal North guide
What the Mesh version's side fans did for the graphics card.
Lian Li V100 fan guide
Why the roof fans did nearly all the work.

Only need intake and exhaust totals? The fan airflow calculator is quicker. To set how fast each fan spins as your PC heats up, use the fan curve tool.

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