Airflow help needed

adrichardson81 · 6 Oct 2019 at 20:11

Hi all

I've just downsized from a Define S to a Jonsbo UMX4 Zone. It's possibly the most challenging ATX build I've done, as there's very little room for manoeuvre.

I've gone for 3 Noctua NF-S12B PWMs (rear and bottom are intakes and the top is the exhaust) and an NH-U12A with stock fans. I'm happy with the GPU setup (and should be switching to a smaller 2080 Super come payday), but could I get a second opinion on the CPU cooling?

The cooler's quite close to the intake, so I'm wondering if the push fan on the heatsink is actually adding anything. Would I be better off moving it to the case intake and just running the cooler as a pull?

Thanks!

EssexBoy · 6 Oct 2019 at 20:37

No front fans? i would have the rear as exhaust imo

2 front 1 rear if you not got any more fans

adrichardson81 · 7 Oct 2019 at 08:01

EssexBoy said:
No front fans? i would have the rear as exhaust imo

2 front 1 rear if you not got any more fans

Front fans aren't an option for this case. Stock configuration is rear intake and 2 top exhausts. The problem is that starves the gpu and I would imagine harms airflow through a tower cooler.

harvey.l12 · 7 Oct 2019 at 11:43

I’d have the rear as the exhaust to remove all the hot air coming from the CPU cooler

adrichardson81 · 7 Oct 2019 at 15:36

harvey.l12 said:
I’d have the rear as the exhaust to remove all the hot air coming from the CPU cooler

I should have mentioned that I flipped the fans on the CPU cooler so it blows towards the front of the case. I'm hoping that convection will help hot air from the gpu to hit the top exhaust, as I don't think it would reach the main exhaust without going through the cpu.

Would setting the bottom fan as a exhaust and using a single intake work? At least the hot air would actively flow away from the gpu...

EssexBoy · 8 Oct 2019 at 05:47

adrichardson81 said:
Front fans aren't an option for this case. Stock configuration is rear intake and 2 top exhausts. The problem is that starves the gpu and I would imagine harms airflow through a tower cooler.

Yea i was looking at the define not the jonsbo sorry.

If possible two intakes at bottom 1 rear exhaust and an aio cpu cooler would be best imo.I don't see the noctua getting the cool air it needs with the gpu heat below it.

Meddling-Monk · 10 Oct 2019 at 23:23

A bit late, but what CPU are you trying to cool with the U12A? And what temps are you getting on the CPU and the GPU under stress with the current setup?

With regards to the fans on the cooler, I wouldn't remove the Push fan on the U12A, the Pull sure if want to remove one, but not the Push one. Not unless you have no other options available as from my experience, the Push fan allows the cooler to perform best when run in single fan config.

Without any further info available, looking at that setup, I'd suggest getting two more fans (2x120mm) for the following:
2x 120mm Exhaust at the top. Since you have two heat throwing items in the case (the U12A and the GPU below it), you'd want to remove as much of the heat as quickly as possible but without causing a negative pressue situation inside the case.
1x 120mm Intake at the rear. This provides the cool air solely for the CPU cooler.
2x 120mm Intake at the bottom. This provides the cool air largely for the GPU.

The reason for this suggestion, is that the CPU can receive its own set of (slightly) cooler air from the rear. I say "slightly", because the GPU will inevitibly throw some heat out the back and so this gets recycled back in via the rear fan into the case in this config.

The GPU will get two fans worth of cooler air from the bottom to cool the GPU, and any remaining air pushes upwards, so it shouldn't be starved of cooler air for cooling. And the general direction of the air being pushed upwards, will run into the CPU cooler that blows inwards towards the front of the case.

The two exhaust fans at the top should help extract the warmed up air within the case, and because you have two hot items and largely postive pressure (from 3x120mm fans as Intake vs 2x120 as Exhaust), most of any warmed up air should exit from the top more easily. And any heated up air that enters the right section behind the cover, should be able to convect up through the top mesh without any issues from the positive pressure.

adrichardson81 · 20 Oct 2019 at 16:54

Meddling-Monk said:
A bit late, but what CPU are you trying to cool with the U12A? And what temps are you getting on the CPU and the GPU under stress with the current setup?

With regards to the fans on the cooler, I wouldn't remove the Push fan on the U12A, the Pull sure if want to remove one, but not the Push one. Not unless you have no other options available as from my experience, the Push fan allows the cooler to perform best when run in single fan config.

Without any further info available, looking at that setup, I'd suggest getting two more fans (2x120mm) for the following:
2x 120mm Exhaust at the top. Since you have two heat throwing items in the case (the U12A and the GPU below it), you'd want to remove as much of the heat as quickly as possible but without causing a negative pressue situation inside the case.
1x 120mm Intake at the rear. This provides the cool air solely for the CPU cooler.
2x 120mm Intake at the bottom. This provides the cool air largely for the GPU.

The reason for this suggestion, is that the CPU can receive its own set of (slightly) cooler air from the rear. I say "slightly", because the GPU will inevitibly throw some heat out the back and so this gets recycled back in via the rear fan into the case in this config.

The GPU will get two fans worth of cooler air from the bottom to cool the GPU, and any remaining air pushes upwards, so it shouldn't be starved of cooler air for cooling. And the general direction of the air being pushed upwards, will run into the CPU cooler that blows inwards towards the front of the case.

The two exhaust fans at the top should help extract the warmed up air within the case, and because you have two hot items and largely postive pressure (from 3x120mm fans as Intake vs 2x120 as Exhaust), most of any warmed up air should exit from the top more easily. And any heated up air that enters the right section behind the cover, should be able to convect up through the top mesh without any issues from the positive pressure.

Thanks. I've gone with 2x NF-S12B as bottom intakes, following the GPU temps (so they'll ramp up even if the CPU load isn't high). Top side, I've got an NF-S12B as intake and exhaust (rear intake, top exhaust), but I'll go with your suggestion and add a 2nd exhaust, as it takes it a while to get the case temp back down after a gaming session.

I've added a Corsair Commander Pro, so fine-tuning should be a bit less hassle now.