[SOLVED] Case fans installation on top

Karadjgne

Titan
Ambassador
None of the above. There were some accurate observations made, but none really smacked it home as they were incomplete.

Fans work by the blades movement creating a low pressure area in front of them. Faster the rotation, stronger the vacuum. The byproduct is a pressure wave out of the back of the fan.

With that, exhaust fans work by creating a low pressure area, and nature abhors a vacuum, so the higher pressure air supplied at the front of the case will physically move to fill the void created. That's airflow.

So you do not want low pressure areas in unwanted or competitive positions, such as anywhere near the cpu cooler fan intake. You will want as much low pressure as possible on the cpu cooler exhaust.

That means only One fan on top, as close to the rear exhaust as is possible, doubling the potential low pressure area, so more air is moved, faster, from front to rear, which has the side affect of feeding more air to the cpu cooler fan, which also has an easier time pushing its air through as there's a stronger vacuum at the rear.

Might not be as pretty or as balanced looking as having 2 fans on top, but it works far better, especially under higher load outputs, which lowers temps everywhere.
 
Reactions: T9shuvo

geofelt

Titan
I would not use any top fans at all.

If set to exhaust, they will redirect the front intake airflow up and out of the case before it can reach the cpu cooler and graphics card.

If all of your airflow comes from one source and is filtered, your parts will stay cleaner.
Top fans will draw in unfiltered air from adjacent openings.

The purpose of a rear exhaust is to direct the cooling airflow over the parts to be cooled. cpu/mobo/gpu.
If you have the fans in hand, go ahead and try the different options.
If considering buying fans for the top, I would not.

If you want better airflow, you can replace the front intakes with higher performing fans. They will be noisier.
 
Reactions: T9shuvo

T9shuvo

Commendable
Mar 30, 2020
7
0
1,510
0
I would not use any top fans at all.

If set to exhaust, they will redirect the front intake airflow up and out of the case before it can reach the cpu cooler and graphics card.

If all of your airflow comes from one source and is filtered, your parts will stay cleaner.
Top fans will draw in unfiltered air from adjacent openings.

The purpose of a rear exhaust is to direct the cooling airflow over the parts to be cooled. cpu/mobo/gpu.
If you have the fans in hand, go ahead and try the different options.
If considering buying fans for the top, I would not.

If you want better airflow, you can replace the front intakes with higher performing fans. They will be noisier.
Thank you, this was very helpful 👍
 

Karadjgne

Titan
Ambassador
None of the above. There were some accurate observations made, but none really smacked it home as they were incomplete.

Fans work by the blades movement creating a low pressure area in front of them. Faster the rotation, stronger the vacuum. The byproduct is a pressure wave out of the back of the fan.

With that, exhaust fans work by creating a low pressure area, and nature abhors a vacuum, so the higher pressure air supplied at the front of the case will physically move to fill the void created. That's airflow.

So you do not want low pressure areas in unwanted or competitive positions, such as anywhere near the cpu cooler fan intake. You will want as much low pressure as possible on the cpu cooler exhaust.

That means only One fan on top, as close to the rear exhaust as is possible, doubling the potential low pressure area, so more air is moved, faster, from front to rear, which has the side affect of feeding more air to the cpu cooler fan, which also has an easier time pushing its air through as there's a stronger vacuum at the rear.

Might not be as pretty or as balanced looking as having 2 fans on top, but it works far better, especially under higher load outputs, which lowers temps everywhere.
 
Reactions: T9shuvo

T9shuvo

Commendable
Mar 30, 2020
7
0
1,510
0
None of the above. There were some accurate observations made, but none really smacked it home as they were incomplete.

Fans work by the blades movement creating a low pressure area in front of them. Faster the rotation, stronger the vacuum. The byproduct is a pressure wave out of the back of the fan.

With that, exhaust fans work by creating a low pressure area, and nature abhors a vacuum, so the higher pressure air supplied at the front of the case will physically move to fill the void created. That's airflow.

So you do not want low pressure areas in unwanted or competitive positions, such as anywhere near the cpu cooler fan intake. You will want as much low pressure as possible on the cpu cooler exhaust.

That means only One fan on top, as close to the rear exhaust as is possible, doubling the potential low pressure area, so more air is moved, faster, from front to rear, which has the side affect of feeding more air to the cpu cooler fan, which also has an easier time pushing its air through as there's a stronger vacuum at the rear.

Might not be as pretty or as balanced looking as having 2 fans on top, but it works far better, especially under higher load outputs, which lowers temps everywhere.
thank you for this 🙏
 

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