Question 13700k+RTX 4090 in Phantom 530 - case airflow concern

[Alpha0mega]

I just upgraded to a i7 13700K and a RTX 4090, and I am reusing my previous build's NZXT Phantom 530 case, simply because it’s spacious, has good air flow and didn’t feel like changing it for no reason. I have replaced old fans, and added more, but now I have a concern about the airflow.



The thing is, given the size of the GPU, I think the current setup is creating an isolating effect for the CPU cooler.
I am using my previous build’s Noctua NH-D15, with two fans.

This is the case fan setup as it is now:
a. 1x 200mm front intake (NZXT)
b. 2x 120mm bottom intake (Corsair ML 120)
c. 1x 140mm rear exhaust (Noctua)
d. 1x 140mm top exhaust (Noctua)


(Forgive the cable mess. Partly because it’s just built, but also the 12VHPWR adaptor and PCI-E cables will have to be dangling in the open until I can get a Seasonic ATX 3.0).

Now look at the size of the GPU and the position of the top drive cage of the case. That drive cage in not removable, and given the front panel design, there is no opening or place to put a fan on the upper front (and the top of the front panel is closed anyway).

Air flow from the front 200mm intake is below the plane of the GPU. There is an overlap between the GPU end and the cage on the Y axis, so the airflow from the 120mm bottom intakes will not easily make its way to the upper area of the case. If I put my hand near the cooler intake fan, I can’t feel any real airflow there.

I am concerned that this will starve the CPU cooler for fresh air once I put all the panels back on. Even more of a concern given how hot the 13th gen runs, and its boost tied to the temps.

So I am thinking of putting a 140mm Noctua fan on the top, towards the front, for intake. This will blow air directly to the CPU cooler intake far from the outside.


Now my concern is what this will do to the overall airflow in the case. While the CPU heat has a path to flow out the case thanks to the rear 140mm fan being positioned right next to the cooler fin stack, the heat from the GPU will be dumped into the case, needing good airflow to remove it.

If I add the 140mm top intake in that position, it should alleviate the CPU cooler being starved for air, but I am concerned that it will create an opposing airflow i.e. the bottom 120mm intakes are moving air into the case flowing towards the top, helped along with the 200mm, where it flows over the components and is currently exhausted by the rear and top.

If I add a top intake, towards the front, it will move air downwards. CPU cooler get fed enough air, but could this now cause a problem with the airflow, so that the hotter air inside, mainly the GPU heat being dumped inside the case, might find it difficult to move out?

 

[In2Photos]

If you already have the fan why not try it out and see what happens? An alternative might be to install 2x120 (or are they 140?) on the front. It looks like the top 120 would be slightly above the plane of the GPU, but it's hard to tell if the front of the case will block it. IMO it looks like the 200mm is slightly blocked off anyway.

 

[CP5670]

You could make the existing top fan an intake. I set up my case that way. It's generally better to have positive pressure and more air inside the case, whether hot or cold.

 

[Alpha0mega]

If you already have the fan why not try it out and see what happens?

It would be difficult to do a consistent, repeatable test, since I am trying to optimize the ingress of air for the CPU cooler, while trying to make sure that the egress of warm air caused by the GPU isn't hindered.

Just wanted to know whether there is prior knowledge of best practices if there is a potential for opposing air currents.

IMO it looks like the 200mm is slightly blocked off anyway.

It's is slightly blocked on the upper right hand corner. But it's probably sub 3-5% of fan area, at most. It shouldn't make any difference, given that the rest of the area is mesh. Reviews had not raised this concern, and praised the air flow of the case when it came out, ages ago.

I think I have a solution to my problem anyway. I am going to do two things. One is put a piece of cardboard inside the drive cage, diagonally, going from the far top, to the inner bottom. That should angle the air from the top intake air more directly towards the CPU intake, mimicking a front intake fan.

I am also using the Fan Control software to set the top intake to really spin up only when the CPU gets warm. Since games rarely cause the CPU to be loaded (even more so at 4k), there will be lower downward pressure during GPU intensive tasks, and the CPU can get enough airflow during high CPU load.

 

[In2Photos]

It would be difficult to do a consistent, repeatable test, since I am trying to optimize the ingress of air for the CPU cooler, while trying to make sure that the egress of warm air caused by the GPU isn't hindered.

Just wanted to know whether there is prior knowledge of best practices if there is a potential for opposing air currents.



It's is slightly blocked on the upper right hand corner. But it's probably sub 3-5% of fan area, at most. It shouldn't make any difference, given that the rest of the area is mesh. Reviews had not raised this concern, and praised the air flow of the case when it came out, ages ago.

I think I have a solution to my problem anyway. I am going to do two things. One is put a piece of cardboard inside the drive cage, diagonally, going from the far top, to the inner bottom. That should angle the air from the top intake air more directly towards the CPU intake, mimicking a front intake fan.

I am also using the Fan Control software to set the top intake to really spin up only when the CPU gets warm. Since games rarely cause the CPU to be loaded (even more so at 4k), there will be lower downward pressure during GPU intensive tasks, and the CPU can get enough airflow during high CPU load.

When this case came out there were no 4090s! In addition, hard drive bays are rarely in the main compartment anymore either. Most cases today that are known for their air flow offer no restrictions on the front of the case. It's all fans up front. That is due to the change in cooling requirements for today's components over the ones from years ago. Like you I have an older case, a Cooler Master RC590. The front of the case is designed for hard drives and 5.25 bays with only a single fan on the front. It works for older, less powerful equipment, but no way would it stand up to anything modern.

Let us know how the mod goes! Hopefully it meets your needs!

 

[Alpha0mega]

When this case came out there were no 4090s! In addition, hard drive bays are rarely in the main compartment anymore either.

That's true. This case is from a time where optical drives were still in general use, hence the top drive bay. The bottom drive bay was for HDDs, and is totally removable, which I removed so the front 200mm intake is completely unobstructed. Unfortunately the top optical drive bay is riveted in.

On the other hand, not having a bottom compartment for the PSU and drives like modern cases do, does allow me to put two 120mm fans that can draw in air unobstructed directly from the outside.

I can put up to three 140mm fans on top (or 2x200mm). I think my cardboard air redirection should able direct the fresh air directly into the path of the CPU, making it similar to the another front fan intake.

As a side note, this case made me a fan (hah!) of 200mm fans. The front 200mm intake moves a crazy amount of air. Even at the slowest setting, it's not only inaudible but my hand can feel a fair breeze even 6-8" away from it. The other fans, including the 140mm Noctuas, while silent, don't produce anywhere as much air flow. And at maximum speed, the amount of air I can feel is impressive, while still being quieter than the 140mm Noctuas and definitely the loud high RPM 120mms, all of which produce less flow.

A pity that 200mm fans are fairly rare, and are often don't have standardized mounting holes.

 

[Stuka87]

A big issue with the current layout is that the airflow is almost entirely a big turbulent mess. Lots of fans, but no sort of cross flow.

The PSU being below the GPU is hurting you too. Not only does it generate heat, but its blocking an important area where could otherwise be pulling in air. The drive cage also messes that area up.

Making some channels with cardboard as you suggest may help out. And actually, what can really help, is actually blocking open areas in the case. As any open area can result in turbulence as air will try to go to the area with the lowest pressure. Which means you can have an intake fan that ultimately has its air blow out a big hole that is next to it. And not that it makes a direct u-turn, but once it loses velocity, turbulence inside the case will take over.

On my O11 Dynamic, and on my old 380T, I purposely blocked off several areas to prevent this from happening. You can actually test for it if you have something that can generate smoke (incense or something can work). You can see where flow is, you can see dead zones where smoke will just sit, etc.

Throwing lots of fans at it may get what you need, but tuning the air flow can often accomplish the same thing, with less fan noise. If you only have one drive, I would suggest cutting down the size of the drive cage and adding a fan there that blows straight into the CPU. You can also try moving the PSU to the front of the case floor, and moving those fans on the bottom back under the GPU. It will involve cutting, but as old as that case is, I think its served its life well, and cutting it a bit isn't a huge loss.