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Question Why do so many computer cases have solid panels in front of the fans and only a small vent on the sides for the intake air?

torlen11cc

Member
Jun 22, 2013
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Why do a lot of PC Cases have solid panels in front of the fans and only a small vent up the sides to intake air? Surely this limits airflow considerably?

Take a look at this case for example:


Are the vents sufficient to intake air in this case? Would you buy a case like this or go for another PC case that has bigger vents / front mesh panel?
 
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VirtualLarry

Lifer
Aug 25, 2001
49,232
5,468
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I personally now prefer cases with mesh fronts, and top vents/fan/rad mounts or blowholes w/fans (like the Antec 302 and 300).

I agree, I don't really trust that those small side-vents are going to move enough air into the chassis to keep everything cool enough.
 
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Jimminy

Member
May 19, 2020
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Most people that design cases probably only follow fashion and artistic trends.

I bet none who design cases have degrees or experience in appropriate engineering fields like thermodynamics or fluid mechanics.

And remember, they can always cover any engineering sin with the phrase "gamer", or a few RGB leds and it will SELL LIKE HOTCAKES :)
 

mindless1

Diamond Member
Aug 11, 2001
5,394
452
126
It looks to me like that has a mesh vent panel going up the entire height of the side of the front, which should be enough for most people considering how few have multiple HDDs in front bays these days, since it also has all those holes in the back and practically the entire top a filtered intake.

It could be worse! Here's an AOpen KF45b. The lone 2mm vent hole is meant to be covered by an AOpen sticker.

Even then, if you merely cut a hole for a 92mm-120mm fan on the front, Bob's yer uncle except for a gaming rig.


kf45b.jpg
 
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piokos

Senior member
Nov 2, 2018
554
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Why do a lot of PC Cases have solid panels in front of the fans and only a small vent up the sides to intake air? Surely this limits airflow considerably?
No, it doesn't. You can easily measure it yourself.
You need just 3 things:
- a case where the front panel (one with side vents) can be removed or opened,
- a basic anemometer (it doesn't have to be perfectly calibrated - you'll only look at deltas),
- ability to run all case fans on constant rpm.

When you measure the output flow (it's usually easier), you'll see that the impact is minimal. Of course if the case is properly designed (like a Fractal Design R6, not some RGB discotheque for $40).

Air compresses really easily. ;)

As for "why" make such front panels:
- esthetics (yes, it is important),
- soundproofing,
- more area for ports, buttons etc.
 

CP5670

Diamond Member
Jun 24, 2004
4,486
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Yes, I don't think this matters that much. You get roughly the same airflow actually going into the case, unless the front openings are tiny.

I do miss the side fans near the video card that cases with metal or acrylic panels used to have. The glass paneled cases don't have them, and they had a decent impact on the GPU temperatures. You don't even need fans necessarily, just an opening for air there.
 

mindless1

Diamond Member
Aug 11, 2001
5,394
452
126
Become ONE (with power tools). It's just a box. How pretty you finish/trim it after putting hole(s) where you want them is up to you.

It's basic sheetmetal and plastic work. There are some useful tools and techniques, like a jigsaw with a metal cutting blade (also works better for plastic than a rougher cut blade, just slower), and masking tape layers over the work surface to not mar it.

There are hole saws for fans, though the larger hole saws start to get expensive and most computer box fans benefit more from flow with a rounded corner square cutout.

You can lay down masking tape, use a ruler and make a grid to drill smaller holes, and countersink them if plastic to get rid of a fuzzy edge on the hole, or just cut slots and slap filter panels behind them, held on with neo magnets if it's a metal panel, and those magnets can come out of old HDDs if you can't wait on some ordered online.

You can make a hole and file it out to put USB3 ports in a plastic bezel, and epoxy them in if there's no other mechanical solution. I realize it seems like a lot of work but it is not that much time once you have the technique down.

Any case is a trade-off, but most can be improved to better suit the needs of the parts in it. I'd almost rather carve new holes in a case than have to scrounge up scrap material to plug up extra holes (sources of dust ingress) where I don't want any, nor do I want 3+ outward facing fans and 2+ times as many filter panels to clean if it's not a high heat gaming system.

You can fabricate 2.5" bays really easy with sheet aluminum. You can put taller legs on so a bottom facing PSU doesn't suck your tea up through it. ;) You can remove the front bezel entirely and just slap a filter panel on with a painted metal u-channel frame around it.

Make your case exactly the way you want it then you aren't looking to buy any more cases, except one more so you have one to put a new build in while you keep using the one it replaces.
 
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UsandThem

Elite Member
Super Moderator
May 4, 2000
13,496
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It depends on the individual case. Some cases with solid panel fronts are practically closed. This doesn't necessarily mean the PC would overheat, but it will likely run hotter and force the fans to run at higher RPMs.

Some examples of "form over function" case designs is a case like the EVGA DG-77. Of course the case can be modified with additional fans, or by adding spacers to the front standoffs. However, some solid panel cases such as the Phantek P600S have wonderful airflow. It also allows users to tilt open (or remove) the front panel when more airflow is needed. It is similar in function of my Be Quier Dark Base 900.

It all comes down to the engineering/design.
 

piokos

Senior member
Nov 2, 2018
554
202
76
It depends on the individual case.
This is probably a good moment to mention that most decent cases come with an intake dust filter. This filter will be the actual airflow bottleneck.

Anyway, it's quite surprising that people have doubts about narrow side vents, but they believe in CPU heatsinks. ;)
 

mindless1

Diamond Member
Aug 11, 2001
5,394
452
126
^ Yeah but those intake filters are usually crap, often little more than thin foam, and can't really be pulled and cleaned much without distorting and don't block much.

I like a nice pleated piece of furnace filter material behind the front bezel, covering the entire bezel area up to the point where you need to use any bays, say for a 5.25" external optical drive, or removable hdd caddy, or fan controller, whatever in the top bay, if you have any at all, then a front bezel that snaps off without any further disassembly of the case.

In some cases if the front bezel does not just snap off, (won't stay on without factory screws holding it in place) you can screw, cement, or epoxy L-brackets on to interface with the front case frame steel and put neo magnets on that.

You can get that pleated furnace filter material for $5 or less, in a size large enough to do 3-4 filter panels. If it's the same filter you use for your regular furnace filter duty, even more convenient to buy the cheaper multi-pack of filters.

That is not just better filtration with insignificant additional flow impedance (due to the large surface area), it's also a fairly universal fix for the average case design where the front bezel has at least a couple cm depth between it and the case frame front.

Granted if you change or upgrade cases or internal build parts more often, it matters less if the filter panels don't last or the parts get upgraded before much dust settles on them, but I know I can go to any hardware store and get a filter that will cut to size and work.
 
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PlanetJosh

Golden Member
May 6, 2013
1,426
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I have both side panels open 1/2 inch at the bottom. But that may create more airflow problems that it solves, not sure.
 

mindless1

Diamond Member
Aug 11, 2001
5,394
452
126
^ It shouldn't be a problem unless it is robbing air from flowing through the HDD rack and you have a stack of them, or your board chipset is in the lower front quadrant and running hot, though arguably that would be a board design problem, if it overheats w/o overclock then it needed a better heatsink from the factory.

Today it's common to find the video card to be the point where more airflow helps and there are software tools to check temperature in different airflow configs.
 

Aikouka

Lifer
Nov 27, 2001
29,481
451
126
I think it was GamersNexus that suggested that a side opening like ones posted earlier should be at least a 1/2" opening, or else you start running into pressure losses. I'm not an expert on this, but I recall hearing something about how air movement needs to be looked at like fluid dynamics.

I ran into what could be the opposite problem with a case one time. I was using a Thermaltake X9 for its spacious nature that worked well with water cooling, and it worked great for that purpose. However, it's high volume created a different problem... due to only having two 140mm fans in the front, there just wasn't enough pressure in the case, causing air to just disperse as it entered rather than flow toward the motherboard and such. So, I ended up with issues keeping some motherboard components -- especially hotter m.2 SSDs -- cool. (One of my m.2 SSDs would throttle at 63C given its max temp listed was 70C.)
 

piokos

Senior member
Nov 2, 2018
554
202
76
I'm not an expert on this, but I recall hearing something about how air movement needs to be looked at like fluid dynamics.
Air is a fluid, so there's no reason why it shouldn't me looked at as one. ;)

But the idea of 1/2" case opening and pressure losses sounds pretty exotic. Could you find the source?
I have both side panels open 1/2 inch at the bottom. But that may create more airflow problems that it solves, not sure.
I don't understand this idea. You're not assembling the case fully or what? Photo?
 

Aikouka

Lifer
Nov 27, 2001
29,481
451
126
But the idea of 1/2" case opening and pressure losses sounds pretty exotic. Could you find the source?
Pretty sure it was in a GamersNexus review of a case that had some rather restrictive openings. I'm pretty sure the figure relates specifically to those sideways openings that force air to make a 90-degree turn. My guess is that it has to relate to the amount of volume that can be pulled combined with the loss of pressure as a result of making the 90-degree turn.
 
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chrisjames61

Senior member
Dec 31, 2013
655
373
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Why do a lot of PC Cases have solid panels in front of the fans and only a small vent up the sides to intake air? Surely this limits airflow considerably?

Take a look at this case for example:


Are the vents sufficient to intake air in this case? Would you buy a case like this or go for another PC case that has bigger vents / front mesh panel?
Mainly because most case manufacturers are not only inept they have the "me-to" mentality and slavishly copy each others "ideas". With a few notable exceptions.
 

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