Discussion Help! Bigger fan = higher temp (Dancase A4)

[daddelbud]

Hi

I've been struggling with heat in my Dancase A4 and decided to upgrade my fan on my NH-L9a-AM4 from the 92mm (A9x14 ) to 120mm (A12x15) with a 120mm fan adapter.
As the 120mm can move double as much air, I hoped that it could cool the same, but with less noise.

But if I run a stress test with 100% load and 100% fan, the thermals are actually worse with the 120mm cooler.

Can anyone help my sheet some lights on what could be going wrong?

My thermals on VRM and chipset have dropped 5 degrees which is good.

Picture of new fan vs old:

Fan adapter:
https://j-hackcompany.com/?product=noctua-nh-l9-120mm-fan-adapter

New fan:

NF-A12x15 PWM chromax.black.swap

Having received dozens of awards and recommendations from international hardware websites and magazines, the NF-A12x15 has established itself as a default choice when it comes to premium-quality slim 120mm fans. The chromax.black.swap edition combines the NF-A12x15’s signature quiet cooling...

noctua.at

 

[Lucas]

I have not run any simulations, but I could try to explain this from a physics standpoint. Fluids want to take the path of least resistance, always. From your images it seems like your new fan is slightly larger than the fins on the heatsink. Because of this the easy path for the fluid (air in this application) is on the sides. I.e, you lose pressure. With the smaller fan, the air has nowhere to go, which means it has to be pushed through the fins.

As said, not sure how large the effects are in this case, but there might be some to it. You could test this by isolating around the fan.

 

[daddelbud]

I have not run any simulations, but I could try to explain this from a physics standpoint. Fluids want to take the path of least resistance, always. From your images it seems like your new fan is slightly larger than the fins on the heatsink. Because of this the easy path for the fluid (air in this application) is on the sides. I.e, you lose pressure. With the smaller fan, the air has nowhere to go, which means it has to be pushed through the fins.

As said, not sure how large the effects are in this case, but there might be some to it. You could test this by isolating around the fan.

Great input, and some of the same ideas I had.
As the temp on the VRM and chipset have went down, air is definitely going outside the heatsink.

The adapter is 6mm tall, do you think the distance between heatsink and fan also could have an impact?

Before the fan was further inside the case, which made be think it sucked air from within the case (and that there was hot air trapped around the cooler). Now its clearly taking in air from outside the case and I can feel it when putting my hand next to the case.

 

[Gilles3000]

The A12x15 also has a larger hub, thus a larger deadzone right under it.

Ideally you'd need a 8-10mm thick ducted adapter. But the shortest i've seen are 20mm, which wouldn't fit in the DanA4.

Personally I'd just upgrade to a better cooler like the AXP-90(full copper) or Blackridge and flip the NH-L9

 

[Diamorif]

Try a 100mm fan. It covers a bit more of the L9a heatsink and still has the same 92mm mounting points. I'm using a no-name 100x15mm fan () on my black ridge in a K39, which has the same cooler height, and its been working great. Scythe and Reeven also make 100x12 or 100x15 fans that might work. you could alternatively try a 92x25mm fan or 100x25 mm fan without the vibration pads. It should just clear in the Dan

 

[daddelbud]

The A12x15 also has a larger hub, thus a larger deadzone right under it.

Ideally you'd need a 8-10mm thick ducted adapter. But the shortest i've seen are 20mm, which wouldn't fit in the DanA4.

Personally I'd just upgrade to a better cooler like the AXP-90(full copper) or Blackridge and flip the NH-L9

Wow... how did I not see that issue, that makes totally sense. Thank you!

Try a 100mm fan. It covers a bit more of the L9a heatsink and still has the same 92mm mounting points. I'm using a no-name 100x15mm fan () on my black ridge in a K39, which has the same cooler height, and its been working great. Scythe and Reeven also make 100x12 or 100x15 fans that might work. you could alternatively try a 92x25mm fan or 100x25 mm fan without the vibration pads. It should just clear in the Dan

Could be an idea, from what I can see the 92mm from the l9a is as powerful or even more powerful than most 100mm. But thank you.

I think maybe for now I will look into a fan shroud.

 

[Diamorif]

Sure, I've done a couple of different builds in the A4 and got a lot of good info from the Youtube channels Optimum Tech and Glob3tech. Globe3tech has an entire playlist of A4 fan and aio testing videos that might be helpful to you as well. good luck with the build.

 

[daddelbud]

Sure, I've done a couple of different builds in the A4 and got a lot of good info from the Youtube channels Optimum Tech and Glob3tech. Globe3tech has an entire playlist of A4 fan and aio testing videos that might be helpful to you as well. good luck with the build.

Thanks I'm also a big fan of Optimum Tech

Can anyone recommend a 120x120x15 fan with PWM and smaller fan-hub?

 

[GuilleAcoustic]

Also, keep in mind that static pressure is important when it comes to heatsink

 

[daddelbud]

Also, keep in mind that static pressure is important when it comes to heatsink

Yeah, I found out
Can you recommend me a fan?

 

[SFF Watercooled]

Noctua fans have a great balance between pressure and airflow.

High-pressure 92mm fans:
Cryorig QT90
Noctua NF-A9x14

High-pressure 120mm fans:
Noctua NF-A12x15
Arctic P12

Noctua makes both the highest pressure fans AND the highest airflow fans, making them super good.