[SOLVED] Case fan curves - intake vs exhaust & recommendation

Jmusic88

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Good day all,

I recently completed a build and overall I am very happy with it. It is much MUCH quiet than my old 10 year old PC that did not have any PWM fans.

My setup :

1. 5 x deepcool RF120 -> 3 at the front acting as intake, 1 exhaust at the rear, and 1 on top acting as an exhaust. The top slot can house 2 fans, but I only have 1 and it sits directly above the CPU fan (slot closest to the rear). rated at 1800 rpm max, 27 dbm. Every fan exhaust the rear exhaust is connecting in a series to one fan headers.

2. 1 x stock AMD Wraith Stealth - CPU is a Ryzen 5 3600. rated at 2700 rpm max, 38 dbm (is what I could find)

3. 2x msi twin frozr GPU Fans. No issues here, just thought to note, but they are silent as they don't really run unless gpu goes above 60C.

4. Case is a Deepcool 55 Mesh

Situation:

Other than the stock fan which is loud at full max, my case fans are rated pretty decently at 27 dbm. But when they run at high rpm, they do get loud, it's more the wooshing air that I hear than anything. Currently, my CPU idles a bit high between 40-50 ish. With web browser it goes to around 55C. The CPU fan runs between 1400-1800 rpm, while deepcool fans run at about 1100-1400 rpm (above 70%!). Note: currently my rear exhaust fans is running 50-100 RPM more than the other 4 fans.

So at idle my PC is quiet loud as I hear air wooshing sounds.

Currently fans are set on PWN through bios, but at a stock curve. I have not inspected the curve much but obivously not working out that well.

Discussion:

I am looking at updating my fan curves, so at idle my case is a little bit more quiet. Probably only having the fans at 50% plus starting at 60C CPU temperature.

1. Should the intake and exhaust fans have the same curve or should intake or exhaust fans have a slightly more aggressive curve? Should I have a positive pressure, so have a little bit of a more aggressive intake curve than exhaust.

2. Should I have the 2 exhaust fans (rear and top) be connected together instead, as currently the top exhaust is controlled together with the front 3 intakes.

3. Can you post your fan curves if you have a similar fan setup so i can compare and perhaps try it?

Please note, I am planning on upgrading my stock cooler to most likely a Nactua nh-u12s, as I think my idle temperatures are a little high. This could change the fan speed with the current PWM set up but I will update the curves from there.

Thank you in advance,
 

madmatt30

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Honestly with that case and that many fans I'd set the front 3 intakes at 1000rpm max and the exhausts at 800rpm max and see if you're happy with noise levels.

There really is no need to set a custom curve if you are, you could run at those set speeds under any scenario and its going to do a decent job.
 

Lutfij

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In the long run, I'd make sure to replace all the fans with Noctua's or Be Quiet's and have all fans and cooler on a PWM hub. That way you need only set a single header on the motherboard to do your bidding(CPU_FAN+hub would do that as well).

As of now, you will need to manually adjust the curve and see if the fans like to be undervolted(that's how they die down and ramp up when temps go down or up).

What is the make and model of your motherboard? Some boards don't have the option to set the heat source for a component(like CPU or GPU or motherboard chipset).
 

Jmusic88

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Mar 11, 2020
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In the long run, I'd make sure to replace all the fans with Noctua's or Be Quiet's and have all fans and cooler on a PWM hub. That way you need only set a single header on the motherboard to do your bidding(CPU_FAN+hub would do that as well).

As of now, you will need to manually adjust the curve and see if the fans like to be undervolted(that's how they die down and ramp up when temps go down or up).

What is the make and model of your motherboard? Some boards don't have the option to set the heat source for a component(like CPU or GPU or motherboard chipset).
Thanks for the reply!

My motherboard is a B450 Gaming plus max (pretty much a tomahawk max).

My fans came with 2 x 4 fan hubs. I could technically put them all in a series and connect them to one header. Would that be a good idea for this? Although right now my cooler isn't the best and its idling temperatures are high, so maybe updating a fan curve to include the cpu would be a bad idea for now.

I actually didn't think I should do this with even the cpu fan. I thought the cpu fan should be by itself and the rest could be connected together.
 

madmatt30

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Honestly with that case and that many fans I'd set the front 3 intakes at 1000rpm max and the exhausts at 800rpm max and see if you're happy with noise levels.

There really is no need to set a custom curve if you are, you could run at those set speeds under any scenario and its going to do a decent job.
 
Even with the stock wraith cooler, I would expect to see 10-15c. over ambient at idle.
Unless you room temperatures are exceptionally high, consider remounting the cooler.
If you did not get it on evenly, it will not cool as well as it can.
Tighten down the screws in a criss-cross pattern a small bit at a time.

I like a constant drone for fan noise. Usually, a fan running at 1000 rpm will be hardly noticeable and will provide sufficient air for cooling.

I like positive pressure. If all of your cooling ari intake comes from one source and is filtered, your parts will remain cleaner. All of the intake air will exit somewhere, taking component heat with it.
The main purpose of the rear exhaust fan is to direct the airflow past the cpu cooler and the motherboard.
The top exhaust fan can be removed.
It tends to draw the airflow up before it reaches the cpu cooler.
Past that, it will tend to draw in unfiltered air from adjacent openings.
You might want to do some experimenting on this.
Try disconnecting the top fan and see what happens.

If you plan on using a fan curve, start it at 500rpm or some fans will not start at all.
I would not fiddle with a curve unless you have some sort of an overheating issue with a big overclock.

NH-U12s is an excellent and quiet cooler. It will come with a couple of low noise adapters.
 

Jmusic88

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Mar 11, 2020
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Honestly with that case and that many fans I'd set the front 3 intakes at 1000rpm max and the exhausts at 800rpm max and see if you're happy with noise levels.

There really is no need to set a custom curve if you are, you could run at those set speeds under any scenario and its going to do a decent job.
I guess I should connect the top exhaust to the same header as the rear fan then eh?
 

Jmusic88

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Mar 11, 2020
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Even with the stock wraith cooler, I would expect to see 10-15c. over ambient at idle.
Unless you room temperatures are exceptionally high, consider remounting the cooler.
If you did not get it on evenly, it will not cool as well as it can.
Tighten down the screws in a criss-cross pattern a small bit at a time.

I like a constant drone for fan noise. Usually, a fan running at 1000 rpm will be hardly noticeable and will provide sufficient air for cooling.

I like positive pressure. If all of your cooling ari intake comes from one source and is filtered, your parts will remain cleaner. All of the intake air will exit somewhere, taking component heat with it.
The main purpose of the rear exhaust fan is to direct the airflow past the cpu cooler and the motherboard.
The top exhaust fan can be removed.
It tends to draw the airflow up before it reaches the cpu cooler.
Past that, it will tend to draw in unfiltered air from adjacent openings.
You might want to do some experimenting on this.
Try disconnecting the top fan and see what happens.

If you plan on using a fan curve, start it at 500rpm or some fans will not start at all.
I would not fiddle with a curve unless you have some sort of an overheating issue with a big overclock.

NH-U12s is an excellent and quiet cooler. It will come with a couple of low noise adapters.
I installed the cpu cooler about 2 months ago and I did do the criss-cross pattern. I installed it using the dot method for the paste. The temperatures have not changed since the install. I did read online though that r5 3600 does idle at around high 40s on a stock cooler, so I figured that I installed it properly.

I can definitely try removing the top exhaust fan and seeing how it behaves. Worst case if nothing changes, would you recommend that I upgrade the cpu cooler first before playing with the curves?
 

madmatt30

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Leave the top rsar exhaust imo, it's fine if it's at the back position, it's when people fill both top exhaust and one is slightly in front of the cpu that a crossflow issue arises.

And yes run the tears together from the same header if possible and drop them down to 800rpm or lower.
You don't need fast airflow in exhausts, just enough to help the airflow along on it way, natural v convection will always push air to the top rear of the case anyway.

I personally prefer set speed on case fans at a balance between airflow and noise, this will be relative to your build and your ears.

Once you get used to a set amount of noise it becomes completely unnoticeable after a small amount of time, to me that's preferable to variable speeds fans ramping up and down.
 

Jmusic88

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Leave the top rsar exhaust imo, it's fine if it's at the back position, it's when people fill both top exhaust and one is slightly in front of the cpu that a crossflow issue arises.

And yes run the tears together from the same header if possible and drop them down to 800rpm or lower.
You don't need fast airflow in exhausts, just enough to help the airflow along on it way, natural v convection will always push air to the top rear of the case anyway.

I personally prefer set speed on case fans at a balance between airflow and noise, this will be relative to your build and your ears.

Once you get used to a set amount of noise it becomes completely unnoticeable after a small amount of time, to me that's preferable to variable speeds fans ramping up and down.
I will definitely give those speeds a try shortly. Based on what you said, I'm assuming your own fan speeds are constant and not variable? (that's the impression that I got).

Regarding to getting used to a sound - I have been using this build for a few months and I still can't get used to the whooshing air and the rpm ramping up. I use headphones for gaming so I don't really notice it, but when I just web browse it bugs me a little.
 

madmatt30

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I will definitely give those speeds a try shortly. Based on what you said, I'm assuming your own fan speeds are constant and not variable? (that's the impression that I got).

Regarding to getting used to a sound - I have been using this build for a few months and I still can't get used to the whooshing air and the rpm ramping up. I use headphones for gaming so I don't really notice it, but when I just web browse it bugs me a little.
Yep I have 2 x 140 intakes limited to 1000rpm and 2 x 120mm exhaust limited to 800rpm.

Ryzen 7 with a 240mm tower cooler, and a 5700xt gpu.

My temps generally sit 60-65c max on both gpu and cpu during heavy usage so the case airflow is fine.

I'm running a solid fronted fractal define at that, your mesh front has way less constricted intakes on the front.

It will be the ryzen cooler that annoys most for you I would imagine, hence my use of an aftermarket.
 

Jmusic88

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Yep I have 2 x 140 intakes limited to 1000rpm and 2 x 120mm exhaust limited to 800rpm.

Ryzen 7 with a 240mm tower cooler, and a 5700xt gpu.

My temps generally sit 60-65c max on both gpu and cpu during heavy usage so the case airflow is fine.

I'm running a solid fronted fractal define at that, your mesh front has way less constricted intakes on the front.

It will be the ryzen cooler that annoys most for you I would imagine, hence my use of an aftermarket.
Thanks for the info. I'll definitely give those a try later on when I get the chance. I'll post an update for sure!

My gpu and cpu temperatures under load are pretty good. The msi twin frozr fans in my gpu is pretty great. It doesn't really run below 60C, and during gaming (not stressing) maximum I get is about 65 as well.

Under load for my cpu (again gaming not stressing) it goes to about 67-70 max. So I know the cooler can keep up. But yeah, it's the most audible fan in my case for sure. That's why I'll go the aftermarket route as well.
 

Jmusic88

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@madmatt30

Alright my top and rear fans are both connected together now. The exhausts are running at 800 RPM max, the intakes are almost at 1000 RPM (980 ish). I can only set these by percentages, I could of tinkered abit to have it exact but didn't want to spend too much time.

The noise is much more acceptable! I did change them to 500-600 RPM for a few secs and they were quiet I liked it but I went back to the 1000/800 RPM combo. I think I am going to test these for now and see if CPU/Motherboard/GPU/etc temperatures are staying as before. If so, I might even reduce the RPM a bit more for some more silentness.. But you were right, I can definitely hear the stock cpu fan now and it is quiet annoying. It has a humming sound that I did notice before because the other fans were masking it. I will definitely upgrade it later on. My GPU did increase by 2-3 degrees but that's because the fans are not spinning below 60C.

However, in case that my temperatures do increase overall during heavy usage, I might end up ramping it up at higher temperatures but for an idle/web browsing scenario it is WAY better.

If I end up ramping it up, what should my fan step up/step-down time be? Currently I have it set as 0.1 seconds (no wonder why my fans were ramping up with every cpu temperature change!).

Thanks again,

P.S. I disconnected the top fan as per one of the suggestions above, but nothing really changed. Just wanted to try it anyhow.
 
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madmatt30

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@madmatt30

Alright my top and rear fans are both connected together now. The exhausts are running at 800 RPM max, the intakes are almost at 1000 RPM (980 ish). I can only set these by percentages, I could of tinkered abit to have it exact but didn't want to spend too much time.

The noise is much more acceptable! I did change them to 500-600 RPM for a few secs and they were quiet I liked it but I went back to the 1000/800 RPM combo. I think I am going to test these for now and see if CPU/Motherboard/GPU/etc temperatures are staying as before. If so, I might even reduce the RPM a bit more for some more silentness.. But you were right, I can definitely hear the stock cpu fan now and it is quiet annoying. It has a humming sound that I did notice before because the other fans were masking it. I will definitely upgrade it later on. My GPU did increase by 2-3 degrees but that's because the fans are not spinning below 60C.

However, in case that my temperatures do increase overall during heavy usage, I might end up ramping it up at higher temperatures but for an idle/web browsing scenario it is WAY better.

If I end up ramping it up, what should my fan step up/step-down time be? Currently I have it set as 0.1 seconds (no wonder why my fans were ramping up with every cpu temperature change!).

Thanks again,

P.S. I disconnected the top fan as per one of the suggestions above, but nothing really changed. Just wanted to try it anyhow.
If you're running in relation to cpu temps/fan speeds set it at 1 second minimum (maybe even 2), it should stop that erratic up/, down ramping of fans.

If you still want to set a higher curve under load you could honestly set minimums as 600rpm exhaust and 800rpm intakes.

Will still be more than enough with that case fan configuration.

The only thing to be wary of is that at lower speeds some fans actually become noisy in a different way, you end up hearing motor noise/hum rather than the movement of air.
Depends on the fan and the person's perception of noise.

Noisy for someone may be virtually silent for someone else.

I personally cannot stand any fan under 100mm.There is a drone to them which I find immensely irritating irregardless of speed.
Built an htpc which only had 80mm fan mounts a few years back, the amount of time and money I spent in the quest for 'quiet' 80mm fans is insane.
 

Jmusic88

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If you're running in relation to cpu temps/fan speeds set it at 1 second minimum (maybe even 2), it should stop that erratic up/, down ramping of fans.

If you still want to set a higher curve under load you could honestly set minimums as 600rpm exhaust and 800rpm intakes.

Will still be more than enough with that case fan configuration.

The only thing to be wary of is that at lower speeds some fans actually become noisy in a different way, you end up hearing motor noise/hum rather than the movement of air.
Depends on the fan and the person's perception of noise.

Noisy for someone may be virtually silent for someone else.

I personally cannot stand any fan under 100mm.There is a drone to them which I find immensely irritating irregardless of speed.
Built an htpc which only had 80mm fan mounts a few years back, the amount of time and money I spent in the quest for 'quiet' 80mm fans is insane.
What do you run your fans in relation to? I did have some options, but I figured cpu temperature is the most logical option since it changes most often.

The humming/motor sound that I hear now comes from the stock cooler which is a bit annoying. I had to make sure, so I opened the glass window and listened. It's more noticeable now that the rest of the fans have quiet down.

I realize your cpu cooler is not the same as mine. But did you touch the curve or the ramp up/ramp down? Mine was on pwm, I changed it to auto but it's the same settings. Otherwise I didn't want to touch anything that directly cools my cpu.

Currently it's at: 0C/20%, 20C/20%, 65C/75%, 70C/100%.
 

madmatt30

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What do you run your fans in relation to? I did have some options, but I figured cpu temperature is the most logical option since it changes most often.

The humming/motor sound that I hear now comes from the stock cooler which is a bit annoying. I had to make sure, so I opened the glass window and listened. It's more noticeable now that the rest of the fans have quiet down.

I realize your cpu cooler is not the same as mine. But did you touch the curve or the ramp up/ramp down? Mine was on pwm, I changed it to auto but it's the same settings. Otherwise I didn't want to touch anything that directly cools my cpu.

Currently it's at: 0C/20%, 20C/20%, 65C/75%, 70C/100%.
Those temps are very good for a ryzen 3600.

The difference is I'm using a 140mm tower cooler with a max rpm of 1200.

Even at full speed its unnoticeable because its internal and its very quiet anyway.

I have it set to silent profile in bios which keeps it between 400-1000rpm max.

Its enough to keep my ryzen 7 around 65c even under stress testing.

The issue with ryzen 3*** is the speed at which temps will spike to 60-70 degrees intermittently even under idle loads, this is enough to make that little wraith fan ramp up to 2000rpm for a couple of seconds and then it takes a further 2 seconds to slow back down, which in turn will ramp the case fans up if their performance is tied into cpu cooler temps.

An aftermarket cooler with a bigger surface area, bigger fan and a lower rpm will be your best purchase possible to reduce noise level, fairly certain you could even lower all those case fans another 200rpm with the right cooler.
 

Jmusic88

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Those temps are very good for a ryzen 3600.

The difference is I'm using a 140mm tower cooler with a max rpm of 1200.

Even at full speed its unnoticeable because its internal and its very quiet anyway.

I have it set to silent profile in bios which keeps it between 400-1000rpm max.

Its enough to keep my ryzen 7 around 65c even under stress testing.

The issue with ryzen 3*** is the speed at which temps will spike to 60-70 degrees intermittently even under idle loads, this is enough to make that little wraith fan ramp up to 2000rpm for a couple of seconds and then it takes a further 2 seconds to slow back down, which in turn will ramp the case fans up if their performance is tied into cpu cooler temps.

An aftermarket cooler with a bigger surface area, bigger fan and a lower rpm will be your best purchase possible to reduce noise level, fairly certain you could even lower all those case fans another 200rpm with the right cooler.
Awesome thanks for the help!
Out of curiosity, what cooler are you using?
 

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