[SOLVED] Did I install cooler fans backward? (Noctua NH-U12A)

acordeon

Honorable
Mar 12, 2015
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Just upgraded my system to a 5600X with new mobo and Noctua NH-12A cooler. Noctua's directions seemed to indicate which fan should go on which side of the cooler, but after install it seems to be blowing toward the front of the case. Here's a pic: View: https://imgur.com/a/3GeGA6u
. The white fan is the back of the case.

So:
  1. I assume I want the CPU fans blowing toward the rear of the case rather than the front?
  2. Can anyone verify from the photo that the fans would be blowing toward the front? I don't see an indicator on the Noctua fans which direction they blow. Is it right that they blow toward the side with the label on the hub?
Thanks!
 

Paperdoc

Polypheme
Ambassador
As Lafong says, look closely. Most fans have moulded into their frames on the outside two arrows. One points around the frame to indicate the direction of rotation of the fan blades. The other points through the frame to show the direction of air flow the fan generates. Mount both fans on the heatsink portion to blow air through it towards the BACK of your case where the white exhaust fan is located.

Do use both fans on the Noctua cooler. They are intended to work together for best performance. Many people expect the wrong things from such a design. Control of these fans is based on the actual TEMPERATURE measured inside the CPU chip. The system adjusts the fan speeds constantly to keep that temperature on target as the workload changes. If you were to remove one fan, that system still would keep the SAME temperatures, but to do that it would make the one remaining fan run faster. Some people look at the unchanged temperature and conclude that removing the fan made no difference. Wrong! Having BOTH fans working means two things that are more subtle. One is that they both will run slower that one fan would, so they may last a little longer. The other is that, at extremely high workloads with high heat removal required, that dual-fan capacity ensures that heat WILL be removed as quickly as needed so your CPU does not overheat.
 

acordeon

Honorable
Mar 12, 2015
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Thanks, GobbleBear, but I think you did not fully understand my question.

they could be taking air from the exterior and providing cool air to the interior, thus making it cooler. besides there are 2 types,

  1. the CPU fan takes air from the outside and directs it towards the cpu,
  2. the other fans take the interior air and puts them outside :)
You seem to be talking about case fans. These are not case fans, they are fans on the CPU cooler.

These are the 2 types of fans, maybe you mistakenly bought the wrong one :( (or that you installed it the wrong side)
I did not buy the two cooler fans separately. They came with the cooler. And they only have a clip on one side. So the only thing I could do different is swap their positions on the cooler.
 

Lafong

Respectable
Dec 2, 2021
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Noctua fans have an arrow on the rim of them that indicates which way air will flow. The arrows aren't easy to see, but they are there.

You want both fans blowing the same way. TOWARD the white fan. TOWARD the rear of the case.

The fan on the back side of the cooler nearest the white fan won't add much cooling power. Maybe 2 or 3 degrees. You might want to use it elsewhere in the case or even remove it and keep it as a spare in case the other CPU fan fails. Not a big deal.
 

Paperdoc

Polypheme
Ambassador
As Lafong says, look closely. Most fans have moulded into their frames on the outside two arrows. One points around the frame to indicate the direction of rotation of the fan blades. The other points through the frame to show the direction of air flow the fan generates. Mount both fans on the heatsink portion to blow air through it towards the BACK of your case where the white exhaust fan is located.

Do use both fans on the Noctua cooler. They are intended to work together for best performance. Many people expect the wrong things from such a design. Control of these fans is based on the actual TEMPERATURE measured inside the CPU chip. The system adjusts the fan speeds constantly to keep that temperature on target as the workload changes. If you were to remove one fan, that system still would keep the SAME temperatures, but to do that it would make the one remaining fan run faster. Some people look at the unchanged temperature and conclude that removing the fan made no difference. Wrong! Having BOTH fans working means two things that are more subtle. One is that they both will run slower that one fan would, so they may last a little longer. The other is that, at extremely high workloads with high heat removal required, that dual-fan capacity ensures that heat WILL be removed as quickly as needed so your CPU does not overheat.
 

geofelt

Titan
Dangle a tissue in front of a running fan to verify which direction the air is flowing.
Looking at the photo it looks to me like the front fan is mounted backwards.
It should be directing airflow through the cooler towards the rear exit.
Check the orientation of the rear fan also.
A slight peek indicates that it is reversed also.
The rear fan is part of the design, I would not remove it.
What you have will work, up to a point, but the cpu heat is going to accumulate in the case which is not effective. You want to get cpu heat out of the case asap.
The rear white fan looks to be properly oriented.

When I first get a noctua fan, I use a sharpie to highlight the fan direction.
 

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