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PC case fan config

Posted on 12/28/20 at 1:19 pm
Posted by reauxl tigers
Tiger Woods Fan
Member since Aug 2014
8742 posts
Posted on 12/28/20 at 1:19 pm
I've done the research before but it's been a while and I don't have time to do it again.

Which fans are ideal for the setup in this pic in terms of CFM and static pressure? I don't plan on doing a push/pull config as I don't think I need to. I achieved a 5Ghz OC benchmark at 1.4v with 2850 RPMs and the CPU temp maxed out at 75*.

Is there any kind of math involved with the CFM and static to help get the best airflow possible? From my understanding, fans with higher static pressure are ideal for pull configs on a radiator and fans with higher CFM are ideal for pushing or pulling a higher volume of air from inside the case?? I'm also familiar with the concept that you need to make sure there's a balance of air coming in vs. air going out. Any advice appreciated.



This post was edited on 11/3/24 at 9:41 pm
Posted by bluebarracuda
Member since Oct 2011
18834 posts
Posted on 12/28/20 at 1:23 pm to
In short, it doesn't really matter that much as long as you have cool air coming in and hot air being exhausted. You'll see very minimal performance differences, if any.
Posted by reauxl tigers
Tiger Woods Fan
Member since Aug 2014
8742 posts
Posted on 12/28/20 at 1:48 pm to
I'm thinking about replacing all the fans and kind of want to have the best air flow possible. If that means adding or removing fans in certain spots, so be it. I'm willing to do the math (if any) involved in getting the air flow out the top and back of the case as consistent as possible.
Posted by bluebarracuda
Member since Oct 2011
18834 posts
Posted on 12/28/20 at 1:54 pm to
You're way overthinking it. For a general gaming PC, it doesn't matter.

Have some fans up front intaking air, have some fans at the top or back exhausting.
Posted by Joshjrn
Baton Rouge
Member since Dec 2008
29858 posts
Posted on 12/28/20 at 10:03 pm to
Ok, you dropped quite a few buzzwords in there, so I'll simplify it:

If your fans are pushing/pulling through anything, whether that be a rad or a dust filter, a static pressure fan will perform better than a standard fan.

Now, with that said:

Just eyeballing it, it looks like we've got three 120s in pull config through a rad as intake, three (presumably) unfiltered 120s across the top as exhaust, and either a 120 or 140 (I can't tell from this angle) that's also presumably unfiltered as exhaust. Also, next time, you don't need the arrows: you shouldn't be taking advice from anyone who can't tell the direction based on the side of the fan they are looking at

My concern with your current setup is whether your case is getting enough fresh air. With the glass off, put your hands behind your intake and just see how much air they are moving. If they are moving a fair amount of air, I wouldn't worry too much about it. If they aren't, first thing I would do is check my rad to see how much dust I've collected. If you've been running it a while, it could probably use a healthy blast of compressed air. Assuming it's clean, then adding some good static pressure fans might help things a bit. But even then, your exhaust fans already outnumber your intake. Add in that your intake is through a rad and your case is likely massively negative pressure. Not only are you going to collect dust, but again, you're just not bringing much cool air in.

Now, because your cpu is cooled through intake air, those temps aren't going to be much affected by that, especially being you are running a 360 rad. But, what do your gpu temps look like? If they are a little more toasty than you would like, I would definitely consider some SP fans on the rad.

Your over arching issue is that NZXT just isn't great for air flow. Your bottom front fan is partially blocked, and your front-most top fan is functionally useless (basically all it does is immediately exhaust cool air from your front intake). So, you're never going to get to perfect, but adding some SP to the front might help a little bit.

Anyway, that's enough of my rambling. Feel free to follow up with more specific questions.
Posted by reauxl tigers
Tiger Woods Fan
Member since Aug 2014
8742 posts
Posted on 12/29/20 at 12:42 am to
Appreciate it, I understood everything you were saying. I’ve got a dust filter on the intake fans so rad should be clean. I was worried about negative pressure because of the fact I have 3 120mm and 1 140mm exhaust fans and just 3 intake fans taking air through a closed front case (with mesh sides fwiw), a dust filter, and a radiator.

I’ve been looking at the Noctua F12s to use as intake fans on the rad. What I need to do is buy some insence sticks to test the air flow. That being said, I’ve never actually checked the intake airflow, just the exhaust fans which seem to be okay, although I don’t really have any frame of reference.

My GPU (2070 super) usually floats around 60C, mostly lower when playing COD. I mounted the rad on the front b/c I’ve heard that’s better for GPU temps than the top of the case.
This post was edited on 12/29/20 at 12:59 am
Posted by boXerrumble
Member since Sep 2011
53951 posts
Posted on 12/29/20 at 7:47 am to
2070 Supers I believe are rated to go up to 83 degrees at stock frequency/voltage curves before starting to dial back clock speeds.

If you're at 60 degrees while gaming, you are more than fine and have nothing to worry about.
Posted by Joshjrn
Baton Rouge
Member since Dec 2008
29858 posts
Posted on 12/29/20 at 9:01 am to
quote:

My GPU (2070 super) usually floats around 60C, mostly lower when playing COD. I mounted the rad on the front b/c I’ve heard that’s better for GPU temps than the top of the case.


60c is perfectly fine. With that said, mounting the rad as intake (location doesn’t matter) is better for cpu temps, not gpu temps. Assuming this wasn’t just a typo, an intake rad uses fresh outside air while an exhaust rad uses air that has been heated inside your case by the gpu. With intake, because the air coming into your case through the rad is being heated to cool your cpu, your gpu temps will be a bit higher, but not by much, and this is preferable because cpus are more temperature sensitive than GPUs.

Anyway, the punchline is that your temps are fine, and it sounds like you’re more itching to change something than you are trying to fix a problem. Nothing wrong with that, but it’s important to keep that in mind.

Oh, and make sure you have a glass of water to ash into and have some windows open; incense burns crazy fast and puts out a ton of smoke, even in just a few minutes that you’re checking case pressure
This post was edited on 12/29/20 at 9:20 am
Posted by bluebarracuda
Member since Oct 2011
18834 posts
Posted on 12/29/20 at 9:25 am to
quote:

With that said, mounting the rad as intake (location doesn’t matter) is better for cpu temps


Mounting the rad in the correct orientation to the pump is more important then anything else
Posted by Joshjrn
Baton Rouge
Member since Dec 2008
29858 posts
Posted on 12/29/20 at 9:44 am to
quote:

Mounting the rad in the correct orientation to the pump is more important then anything else


I meant that “location doesn’t matter” in response to his referring to a “front” rad being better for cooling than mounting it at the “top”. Yes, under no circumstances should your pump be the highest point in your loop, but considering he can’t put a rad at the bottom of that case, it’s literally impossible for him to have that problem. And ideally his hoses would be down, but unless he’s dealing with water noise, that’s not important, and has nothing to do with performance.
This post was edited on 12/29/20 at 9:45 am
Posted by reauxl tigers
Tiger Woods Fan
Member since Aug 2014
8742 posts
Posted on 12/29/20 at 2:23 pm to
Update, just as I suspected, there's some negative pressure under the back exhaust and IO shield. Guessing I need stronger intake fans on the radiator? Either that or deactivate the 3 top exhaust fans? I'll test that and see if anything changes.
Posted by Joshjrn
Baton Rouge
Member since Dec 2008
29858 posts
Posted on 12/29/20 at 2:45 pm to
quote:

Update, just as I suspected, there's some negative pressure under the back exhaust and IO shield. Guessing I need stronger intake fans on the radiator? Either that or deactivate the 3 top exhaust fans? I'll test that and see if anything changes.


So, first thing I would do is unplug your front most top fan. Like I said, that fan is probably doing more harm than good. I wouldn't turn them all off, though. I would also put my hand behind my intake fans and see if I'm comfortable with how much air is blowing. If you aren't, (I know I said this already, but...) check the rad. I know you said it's filtered, but you'd be surprised how much dust gets through, anyway. Assuming it's relatively clean, then I would look at getting some solid SP fans if you're still unhappy with your intake airflow/case pressure.
Posted by reauxl tigers
Tiger Woods Fan
Member since Aug 2014
8742 posts
Posted on 12/29/20 at 3:07 pm to
Update again: Checked rad, pretty clean, dust filter loaded with dust. Unplugged top front fan, not much changed, unplugged all 3 and the negative pressure under the IO shield pretty much disappeared. Turned my rear exhaust fan up a little bit and there was still no negative pressure. However when I turned my GPU fans on, the negative pressure returned I guess because the fans are right there in front of the mounting brackets.

I'm sensing the best thing I can do is get some strong SP fans for the intake on the radiator. The current fans are only 2.3 mm H20 and 87.6 CFM but the Noctuas I'm looking at are 7.6 mm H20 and 109.8 CFM. So the solution seems pretty obvious...
This post was edited on 12/29/20 at 3:09 pm
Posted by Joshjrn
Baton Rouge
Member since Dec 2008
29858 posts
Posted on 12/29/20 at 3:17 pm to
Now, the thing to be cognizant of is that while negative pressure isn’t ideal, your case isn’t great with airflow. You’re getting negative pressure under there, like you said, because your gpu is sucking air. It’s currently able to get cool air through those case holes. If you focus on reducing exhaust, you could very well end up with less airflow in, which should be avoided.
Posted by reauxl tigers
Tiger Woods Fan
Member since Aug 2014
8742 posts
Posted on 12/29/20 at 3:43 pm to
Thanks again for the advice. I've watched a Gamers Nexus TY video on the case I have and they say it's got pretty serviceable airflow especially if you remove the front panel. Some stuff about brute force.
Posted by Joshjrn
Baton Rouge
Member since Dec 2008
29858 posts
Posted on 12/29/20 at 3:52 pm to
So, it’s much, much better without the front panel. But even then, it’s not great, especially with a rad. Steve talking about “brute force” was saying that it had enough space for fans that you could overcome the limitations, but again, having the rad as your intake complicates things.

If you don’t mind the effort of moving shite around, I would be curious how negatively your cpu temps would be affected by putting your rad on the top as exhaust, as that would immediately solve your pressure problem.
Posted by Joshjrn
Baton Rouge
Member since Dec 2008
29858 posts
Posted on 12/29/20 at 4:17 pm to
Because as an addendum, moving your rad up top *will* make your cpu temps go up, which could make your OC unstable. So only try it if you’re itching to frick around with your rig and don’t mind moving it back if it doesn’t work out.

But that’s the vibe I’m getting from you, so I’m trying to meet you where you are

Eta: and you should know you get no judgment from me. I do shite like that all the time. My last change was adding a usb 3.0 extension so I could make a sharp turn with a 90 degree mobo adapter
This post was edited on 12/29/20 at 4:19 pm
Posted by reauxl tigers
Tiger Woods Fan
Member since Aug 2014
8742 posts
Posted on 12/29/20 at 5:59 pm to
I definitely like to frick around with things every now and then. If something catches my attention, it will consume me for an entire week.

I already knew my fan setup was kinda weird and I had planned on improving it a while back and never got around to it.

I will definitely try the top mounted radiator. My CPU is OC'd to 5Ghz @ 1.4v right now and it never gets hotter than 71* at max load, 2850 RPM. My fans run under 70% when idle. Given that I don't play any games that are close to CPU intensive, I might give it a shot and if I have to run the fans at higher RPM to keep it cooler, so be it. They're pretty quiet anyway.

This post was edited on 12/29/20 at 6:09 pm
Posted by Joshjrn
Baton Rouge
Member since Dec 2008
29858 posts
Posted on 12/29/20 at 6:06 pm to
Your fan setup is actually very normal. The issue you’re running into is that you have one bank of intake, and that’s getting impeded by your rad. If your case had bottom intake, you would have a bit more flexibility. That’s why I have nine fans in my case
Posted by reauxl tigers
Tiger Woods Fan
Member since Aug 2014
8742 posts
Posted on 12/29/20 at 6:09 pm to
Do you mean a push or pull config at the top? Would it even matter given it would be warm air moving through the radiator?
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