Front fans vs front-side fans?

[katie279]

Hi all, just a quick question.

Designing a case at the moment and just thinking through airflow/fan layouts.

One quick question is that I see most PC cases have intake fans at the front, ie like:

Corsair iCUE 7000X RGB Tempered Glass Full Tower Smart Case - White (CC-9011227-WW)

Order Corsair iCUE 7000X RGB Tempered Glass Full Tower Smart Case - White (CC-9011227-WW) now online and benefit from fast delivery.

www.overclockers.co.uk

And others have them at the side of the front (sorry, don't know the correct way to describe this!), but like this:

Phanteks NV7 D-RGB with Front and Side Glass Panels Full Tower Case - Black

Order Phanteks NV7 D-RGB with Front and Side Glass Panels Full Tower Case - Black now online and benefit from fast delivery.

www.overclockers.co.uk

Is there any pros or cons of these two designs?

Just wondering if airflow or anything else is affected more by one approach?

 

[Meddling-Monk]

I think airflow is not really impacted that much and even if it was impacted on, it'll largely be negligible unless if you have the fans are a super low rpm where barely anything is running and you only have the front(side) fans going (as it'll need to go a right angle then and not enough pressure to push it through despite the change of direction). So long as you have some exhausting out the back along with those front(side) fans, it should be comparable.

Incidentally I think it's probably going to do more for fan vibration noise (escape) than anything else as a side effect of that positioning. As whilst we can isolate fans from the case through silicone mounts, etc. The one thing you can't really stop is echoes coming out from fan mount locations (other than covering the fan spots up). And in the case of direct front to back fan positions, there's a greater amount of noise that can be let back through (front fans caused noise echoing out the rear fan for example and same in reverse as they're in roughly the same z axis). Whilst with the front(side) fan location, you have less of this, because the rear fan is aimed towards a glass (solid) front panel, and the front(side) fans are doing the same as well unlike in the traditional fan positioned case design.

 

[katie279]

Hey, thanks for this - some really clever points - totally agree on the acoustic point, that makes a lot of sense.

I'll be building out of hardwood, so think it'll be waaaay better than standard metal/glass for acoustics, but still!

Cool, think I'll design for a front-side fan intake then!!

 

[bimbleuk]

Having built both the front fan (Phanteks P400/500) and front side fan (Lian Li OD11 mini) case styles recently I would recommend 140mm where possible but especially if there's a direct path to you to reduce noise. I tend to favour at least 2 x 120mm fans in the bottom feeding the GPU which can be horizontal or vertically mounted with decent air fed to it.

Most of my builds end up with a top mounted 240mm AIO though a decent tower cooler like the Thermalright Assassin series work very well on mid-power CPUs with decent front to back + some top exit flow.

Having said that my own personal daily system is a NR200P MAX mini-ITX case with a perforated side panel. 2 x 120mm slim bottom exit fans and 2 x 140mm top exit fans through an AIO. The combination of 7800X3D + RTX 4080 both with power optimisations is the quietest system I've owned but with top notch performance. If I fit the tempered side panel then flipping the 2 bottom fans to intake as well as the top exit fans gives the best temps.

 

[katie279]

Cool - helpful ideas!

Yes, I'm building a similar build (4090 + 7950x + 96GB + 8tb NVME) - have got :

- a 420mm AIO fan for the top
- 3 x 140mm front/side intake
- 1 x 140mm exhaust at back
- PSU self-contained intake>exhaust

Should give plenty of airflow whilst keeping negative pressure (can adjust with PWM setting if need be)

 

[mickyflinn]

I like bottom intake fans feeding cool air up to the GPU would also consider that.

 

[katie279]

Interesting thought - my concern would be whether this would start becoming a carpet muncher for dust?

I've posted a starter thread here for the project!

Whisperwood

Hi all, Starting a PC build - looking to play mainly solitaire and use for a bit of Word letter writing, so thanks to all your advice I've gone with following specs, which apparently should be able to just about run them without too much lag: Specs: GPU: RTX 4090 CPU: AMD 7950x RAM: 96GB HDD...

forums.overclockers.co.uk

 

[mickyflinn]

Interesting thought - my concern would be whether this would start becoming a carpet muncher for dust?

I've posted a starter thread here for the project!

Whisperwood

Hi all, Starting a PC build - looking to play mainly solitaire and use for a bit of Word letter writing, so thanks to all your advice I've gone with following specs, which apparently should be able to just about run them without too much lag: Specs: GPU: RTX 4090 CPU: AMD 7950x RAM: 96GB HDD...

forums.overclockers.co.uk

Lol.

Dust filters solve that.

I'll have a look.

 

[katie279]

Yes, was just designing a 3d printed cartridge to re-use my laddered tights!

Apparently nylon seems to outperform all the standard mesh dust filters by a mile, so I figured I'd make something to solve it - so I might take you up on that idea...! You'll see I've already got the PSU intake there, so could easily add some extras!

 

[pastymuncher]

It does actually. Many of us used to knick a pair of the wife's tight's/stockings to use as dust filters back in the day. I actually only removed some from my 200mm fan filters last week as they were old and laddered and looked terrible. Unfortunately wifey doesn't buy tights or stockings anymore as she purely wears trousers so I can't knick another pair so have been trying it with the standard dust filter and it's not catching as much as the tights did.

 

[katie279]

Ah, is that why you stole your wife's tights was it Pastymuncher???

Well I certainly get through enough, so I should have an endless supply! I'll need to do a test video once I've decided on my fan cartridge design and test airflow rates of different deniers, M&S vs the rest etc!

 

[Drumroll]

The NV7 should give you better temps because of bottom intake.
Considering that the main offender is the GPU, feeding cool air straight to it, unobstructed, also for the PCH and the NVMEs, bottom intake is king. Side intake, at reasonable rpm/noise should be plenty to feed the AIO on the top as exhaust or an air cooler.
The 7000d Airflow, not the X, was good, the CPU cooler or top AIO won’t ever struggle with lack of cool air from front or side intake (or both). The case is huge and airflow shouldn’t be an issue, but doesn’t matter how you try, your GPU won’t ever be as cool as it would in the NV7 or any other O11D “inspired” design.
Under load should be close enough, but in the 7000d the GPU’s fans will be at higher rpm to achieve similar performance, being louder. Most decent fans at 40-50% won’t be anywhere near the GPU’s fan under load for noise.

 

[katie279]

Cool - useful expertise!

To your point on GPU and cool air to it, do you think it would be worth building custom ducting to direct air directly to it from one of the front fans? I've seen a few videos that suggest you get good results from this?

 

[Drumroll]

don’t get me wrong, the 7000d is huge and you won’t struggle for airflow. My point is that the NV7 is better because of the bottom intake. The 7000d can be very close in performance, but would require higher rpm to achieve that.
Also, the fans are quite far from the motherboard and GPU so, depending on the fan used, you can still get good intake, but not as direct as one would expect. That’s more to do with the air “tunnel” created by the fan. Some fans focus on “spreading” the airflow, maybe better performance if used on radiators and heatsinks? Others, like the Arctic P12 are more centred, if that makes sense. Even at some distance, the majority of its airflow would be in “aligned” to its centre hub.
I know that most people will populate the side intake in the 5000d/7000d and remove the cover that deflect the airflow to the motherboard.
Ideally you can have most decent fans at 20-25% without being intrusive, if using the side cover. That’s plenty of airflow for everything in the motherboard and somehow moving some of the heat that most GPUs exhaust (from the side), towards the motherboard, increasing the temperature from your main NVME and the PCH.
If not using the side cover, my advice is to keep the side intake at low rpm, again 20-25% max. That should just complement the front intake, but not strong enough to deflect the front intake to the point that it won’t reach where you want.
Some people choose to use an AIO on the side, but for me doesn’t make any sense, as if using as exhaust, most of the front intake will be “used” straight away. Top exhaust fans won’t have much use there.
If using a top AIO as exhaust, you should have the best scenario. Also, go big: Arctic Freezer II 420 or any other 420mm AIO. Is a big case. Heavy. Even with dual 420mm EK 40mm thick rad, 3080 waterblock vertically mounted, the case didn’t look quite full.

 

[katie279]

Yeah cool - have gone with the arctic freezer 420, so that'll be perfect I think.

Just to be clear, I'm not planning on using these cases, was just meaning as a reference - I'm planning to build one, as per:

Whisperwood

Hi all, Starting a PC build - looking to play mainly solitaire and use for a bit of Word letter writing, so thanks to all your advice I've gone with following specs, which apparently should be able to just about run them without too much lag: Specs: GPU: RTX 4090 CPU: AMD 7950x RAM: 96GB HDD...

forums.overclockers.co.uk

Gotta do things the hard way.....

 

[Drumroll]

Yeah cool - have gone with the arctic freezer 420, so that'll be perfect I think.

Just to be clear, I'm not planning on using these cases, was just meaning as a reference - I'm planning to build one, as per:

Whisperwood

Hi all, Starting a PC build - looking to play mainly solitaire and use for a bit of Word letter writing, so thanks to all your advice I've gone with following specs, which apparently should be able to just about run them without too much lag: Specs: GPU: RTX 4090 CPU: AMD 7950x RAM: 96GB HDD...

forums.overclockers.co.uk

Gotta do things the hard way.....

Amazing project.
Just to sum things up, direct airflow would allow the dedicated fans from CPU cooler/GPU heatsink to work less, as there’s another fan doing their job/helping them. Indirect airflow would offer cool air for those fans to work, but when the GPU have its fan in 0db mode, only passive cooling would occur, until the fan kicks in.
More important than direct or indirect airflow is good airflow. I’ve always used positive pressure, and only use exhaust to either help direct the flow inside the case or to remove residual heat.
As I’m using the Fractal North mesh now, front intake T30s, 40%, 2K mode. Top exhaust 20%, rear exhaust 25%. PCH temperature is 4C higher than it was in the NV7. The 4080 is reaching the same temperature, within margin of error, but to achieve that its fans are about 200rpm faster. Not a deal breaker, but as the rest of the system is dead quiet, I can notice the higher rpm.
For 99% of the time, the perfect airflow should be similar to the Torrent, which doesn’t even include a rear exhaust. Air will escape where it can, as fast as it can. You should allow the cool air to reach where you want, before exhausting it, reason why I always use the AIO as exhaust on the top.

 

[katie279]

Excellent advice - makes perfect sense, ok I'll have a good think about this! I feel some testing coming on....