AIO Radiator Placement: Front or Top?
Most guides say to put your AIO radiator on top to keep the graphics card cool. In our 3D runs of popular cases, that rule didn't hold up.
Pick your case, card and radiator size to see how warm the card ran with the radiator in each spot.
Your result
Comparing the radiator spots
Graphics card temperature in each spot. Pick one to open it.
PC Airflow Simulator
Run your own build in each spot
Open this radiator layout in the 3D PC Airflow Simulator with your card already in place, then move the radiator and run it again.
What We Found
- A front or side radiator kept the card as cool or cooler. At the same radiator size, that held in 80 of 81 case and card matchups, and the top ran up to 5 °C warmer, with an RTX 5090 in the Corsair 4000D Airflow.
- A front or side radiator always gives the CPU cooler air. It breathes room air, while a top radiator breathed case air at 22 to 32 °C.
- So pick the front or side if it fits. Check that your graphics card still fits with a radiator there first.
Every Radiator Spot in Each Case
We ran each case in our 3D airflow model with every fan spot filled, then moved only the radiator. Front, side and bottom fans blew in, and top and rear fans blew out, so the radiator's fans kept their direction in every spot.
Each run used a Ryzen 7 9800X3D in games and the case's own three-fan graphics card at the picked card's full gaming power, in a 21 °C room. Every fan spun at 1,200 RPM. The table shows three of the 9 cards, and the tool above has them all.
| Case | Radiator spot | RTX 5060 | RTX 5070 Ti | RTX 5090 |
|---|---|---|---|---|
| Corsair 4000D Airflow | Front 360 mm, blowing in | 67 °C | 69 °C | 80 °C |
| Front 240 mm, blowing in | 66 °C | 67 °C | 77 °C | |
| Top 240 mm, blowing out | 66 °C | 69 °C | 82 °C | |
| NZXT H5 Flow (2024) | Front 360 mm, blowing in | 65 °C | 65 °C | 74 °C |
| Front 240 mm, blowing in | 65 °C | 65 °C | 74 °C | |
| Top 240 mm, blowing out | 65 °C | 66 °C | 77 °C | |
| Lian Li O11 Dynamic EVO | Side 360 mm, blowing in | 64 °C | 65 °C | 74 °C |
| Side 240 mm, blowing in | 65 °C | 65 °C | 75 °C | |
| Bottom 360 mm, blowing in | 68 °C | 67 °C | 75 °C | |
| Top 360 mm, blowing out | 65 °C | 66 °C | 77 °C | |
| Top 240 mm, blowing out | 65 °C | 66 °C | 76 °C | |
| Typical mesh-front mid-tower | Front 360 mm, blowing in | 67 °C | 68 °C | 80 °C |
| Front 240 mm, blowing in | 65 °C | 66 °C | 76 °C | |
| Top 240 mm, blowing out | 65 °C | 66 °C | 77 °C | |
| Typical full tower (140 mm fans) | Front 420 mm, blowing in | 65 °C | 64 °C | 72 °C |
| Front 280 mm, blowing in | 64 °C | 63 °C | 71 °C | |
| Top 420 mm, blowing out | 64 °C | 64 °C | 73 °C | |
| Top 280 mm, blowing out | 64 °C | 64 °C | 73 °C | |
| Typical glass dual-chamber case | Side 360 mm, blowing in | 64 °C | 64 °C | 73 °C |
| Side 240 mm, blowing in | 63 °C | 63 °C | 71 °C | |
| Bottom 360 mm, blowing in | 68 °C | 68 °C | 78 °C | |
| Bottom 240 mm, blowing in | 68 °C | 68 °C | 78 °C | |
| Top 360 mm, blowing out | 64 °C | 65 °C | 74 °C | |
| Top 240 mm, blowing out | 64 °C | 64 °C | 73 °C |
Why a Top Radiator Can Warm the Card
The usual advice goes like this. A front radiator blows the CPU's heat over the graphics card, so Noctua suggests a top radiator for the coolest card, and a front one for the coolest CPU.
The CPU's heat is only part of the story, though. In games, a fast card makes several times more heat than the CPU, and most of it leaves through the roof. A radiator is dense, so on the roof it slows that hot air down.
In the 4000D Airflow with an RTX 5090, the air reaching the card was 37 °C with a top 240 mm radiator, against 33 °C with the same radiator up front. A slower roof cost the card more than the CPU's heat did.
What Each Spot Does for the CPU
A front, side or bottom radiator breathes room air, the coolest air your PC can get. A top radiator breathes air from inside the case, which the card has already warmed: 22 to 32 °C in our runs, against 21 °C in the room.
A radiator can only cool its liquid toward the temperature of the air passing through it. So warmer air at the radiator means a warmer CPU.
Which Spot to Pick
If a front or side radiator fits your case, it's the stronger pick. It gives the CPU room air and keeps the card about as cool, or cooler, than the same radiator on top.
Two results surprised us. In the typical mid-tower, a front 360 mm radiator ran an RTX 5090 at 80 °C, warmer than a top 240 mm one at 77 °C. And in the glass dual-chamber case, a bottom radiator was the warmest spot, at 78 °C against 73 °C on the side.
Check the fit first, because a radiator up front takes room from the graphics card. Corsair cuts the 4000D Airflow from 360 to 340 mm with one, and NZXT says the H5 Flow (2024) can lose up to 60 mm.
Your own case and fans can still flip the result, since many of the gaps are only a few degrees. That's why it pays to try your exact case, card and radiator in the PC Airflow Simulator before you mount anything.
Wherever it goes, keep the pump lower than the top of the radiator. Corsair explains that air collects at the highest point of the loop, and you want it in the radiator, not the pump.
Planning the rest of your fans? The PC airflow calculator checks your intake and exhaust balance, and the fan curve calculator helps you pick speeds that stay quiet until you game.