Question Replacing top exhaust fan

[SilentMel0n]

I have just upgraded my NZXT H510 Flow case fans to 3 Corsair LL120 (2 intake and 1 exhaust at the back of the PC) and have used one of the pre-existing case fans in my H510 at the top of case to exhaust. This stock case fan is quite loud though so I was wondering what fan would be good to upgrade this to? Would a 140mm fan here work well? I'm not bothered about RGB up top because my LL120's already provide a nice amount.
Furthermore, I find that barely any air is being exhausted through my back case fan. It seems to be the top fan doing the majority of the work. Is this a problem? Thank you!

 

[Lafong]

Fan Support per NZXT spec sheet:

https://nzxt.com/product/h510-flow


Front: 2 x 120mm / 2 x 140mm

Top: 1 x 120mm / 1 x 140mm

Rear: 1 x 120mm

Filters: All air intake

So, 140 mm is OK front and top; not OK back.

Noctua replacements would be the typical choice for "quiet".

How or where air is exhausted is less important than temps...which you don't state.

 

[SilentMel0n]

Fan Support per NZXT spec sheet:


Front: 2 x 120mm / 2 x 140mm

Top: 1 x 120mm / 1 x 140mm

Rear: 1 x 120mm

Filters: All air intake

So, 140 mm is OK front and top; not OK back.

Noctua replacements would be the typical choice for "quiet".

How or where air is exhausted is less important than temps...which you don't state.

Hey thanks for the reply. I have 1 rear 120mm exhaust and one top 120mm exhaust.

 

[Lafong]

I have 1 rear 120mm exhaust and one top 120mm exhaust.

OK.

What is your next move...if any?

Temps are?

Worry level is?

 

[SilentMel0n]

OK.

What is your next move...if any?

Temps are?

Worry level is?

Well I would like the top fan to be quieter. The temps are fine (hovering 70 degrees CPU when gaming). Is it okay to have a 140mm exhaust when my other exhaust is only 120mm? I heard something about not wanting more intake than exhaust and both my intakes are 120mm.

 

[Lafong]

Current top 120: have you attempted to run it at lower speed via a control available in BIOS?

It's OK to have a top 140 when exhaust is 120.

I wouldn't get caught up in any "advice" unless it generates problems for you.....noise problems, temp problems, dust problems, or WORRY!!!!! problems.

Experiment if you want.

Disconnect this fan. Evaluate temps and noise.

Disconnect that fan. Evaluate temps and noise.

What helps and what hurts....make note of that.

If you cannot reduce RPM on any fan and noise remains your problem, buy fans that spin slower or are known to be quieter.

Any fan at 1500 rpm is likely audible. At 800 maybe not. At 500 probably not.

Your motherboard: are it's fans connectors 3 pin, 4 pin, or some of each?

You have to compromise between temps and noise. Some people would have a stroke if temps were 75. Some people don't care about noise. Don't know about you personally....which is all that really matters.

 

[SilentMel0n]

Current top 120: have you attempted to run it at lower speed via a control available in BIOS?

It's OK to have a top 140 when exhaust is 120.

I wouldn't get caught up in any "advice" unless it generates problems for you.....noise problems, temp problems, dust problems, or WORRY!!!!! problems.

Experiment if you want.

Disconnect this fan. Evaluate temps and noise.

Disconnect that fan. Evaluate temps and noise.

What helps and what hurts....make note of that.

If you cannot reduce RPM on any fan and noise remains your problem, buy fans that spin slower or are known to be quieter.

Any fan at 1500 rpm is likely audible. At 800 maybe not. At 500 probably not.

Your motherboard: are it's fans connectors 3 pin, 4 pin, or some of each?

You have to compromise between temps and noise. Some people would have a stroke if temps were 75. Some people don't care about noise. Don't know about you personally....which is all that really matters.

Great reply, thank you. All 4 case fans are currently plugged in to a fan hub so I don't think I can manually adjust speeds of individual fans. My two front intakes and rear exhaust is 4 pin whilst the top fan is 3 pin. Would it be best to connect this 3 pin separately to my motherboard so I can run it slower?
I used my hand to feel and feels as though most air is being sucked from my heat sink out of top exhaust... seems like almost no air is making it to back fan.

 

[Lafong]

Repeat question: Your motherboard: are its fans connectors 3 pin, 4 pin, or some of each?

How many of each??

What is the over-riding reason you need to use a fan hub if it prevents individual fan control?

 

[SilentMel0n]

Repeat question: Your motherboard: are its fans connectors 3 pin, 4 pin, or some of each?

How many of each??

What is the over-riding reason you need to use a fan hub if it prevents individual fan control?

I have 5 fan connectors on my motherboard, all of which are 4 pin. I used the fan hub as I dont have enough space. My motherboard includes CPU_FAN, CPU_OPT (which I was told not to plug a case fan in to) and SYS_FAN 1/2/3

 

[Lafong]

OK.

Stipulated that you must use that fan hub.

Main complaint: top fan noisy.

Disconnect it.

Evaluate noise and temps.

Report back.

If temps unacceptably high with top fan disconnected, you could:

1; Move one of your other fans to that location and re-evaluate.

2; Buy a new "quiet" top fan, likely 140 mm, that can spin at 1000 rpm or lower via your fan hub.

3; if driven semi-crazy by noise, replace all fans; probably not necessary. I'm not familiar with Corsair LL 120 fans.

Top fan is 3 pin and presumably spins at some RPM that you find too noisy.

I don't know how much your CPU cooler is contributing to overall noise. Maybe little or maybe lots.

I have NO idea how much speed control you would ultimately have with 4 pin fans connected to your fan hub. I use direct connections, not hubs.

 

[Karadjgne]

The nzxt H510 flow uses 1500rpm AER-F fans, which should be very quiet. The LL120's are also 1500rpm fans, so pwm/rpm should be similar.

However, the AER fans are high cfm, 63 at 100% vrs the LL which are static pressure fans and lower cfm, 43 at 100% and it's not a linear line as rpm drops.

Basically, the reason why it seems the AER is doing the lions share of the work, is because it is. Can't compare the miserable cfm from a LL with a high cfm fan. At 50% fan speeds, the LL will be lucky to flow 20cfm, whereas the AER is closer to double that amount.

The only way to get any performance out of the LL is to set it on its own curve, not joined with the AER. Putting the LL at closer to 80% to match the AER at 50%.

Thatll cut down on the AER's noise output and raise the LL airflow output. You don't want to get rid of the AER, as that'll get rid of its high airflow, which is very important at exhaust, unless replacing it with something equitable.

You'd be better of dumping the rear LL exhaust and putting another stock AER in its place if keeping them on the same header.

 

[SilentMel0n]

The nzxt H510 flow uses 1500rpm AER-F fans, which should be very quiet. The LL120's are also 1500rpm fans, so pwm/rpm should be similar.

However, the AER fans are high cfm, 63 at 100% vrs the LL which are static pressure fans and lower cfm, 43 at 100% and it's not a linear line as rpm drops.

Basically, the reason why it seems the AER is doing the lions share of the work, is because it is. Can't compare the miserable cfm from a LL with a high cfm fan. At 50% fan speeds, the LL will be lucky to flow 20cfm, whereas the AER is closer to double that amount.

The only way to get any performance out of the LL is to set it on its own curve, not joined with the AER. Putting the LL at closer to 80% to match the AER at 50%.

Thatll cut down on the AER's noise output and raise the LL airflow output. You don't want to get rid of the AER, as that'll get rid of its high airflow, which is very important at exhaust, unless replacing it with something equitable.

You'd be better of dumping the rear LL exhaust and putting another stock AER in its place if keeping them on the same header.

Thank you for the very informative reply.

This does raise a few questions for me though. Firstly, is it an issue that my AER fan is doing the lionshare of the work? Ie. Is it more efficient to be exhausting air through the top or through the rear of my system or does it make no difference?

Secondly, would replacing the AER (and using a separate fan header on my mobo) with a Noctua NF-P14s (140mm) make any difference? If no, could you suggest a suitable fan to replace the AER?

Thanks again.

 

[Karadjgne]

1) depends on the cpu cooler. With a tower style cooler, air is drawn in the front and most of it is shoved out the back, right at the rear exhaust area, so a rear exhaust fan is somewhat important as far as directly pulling that hot cooler exhaust straight out of the case. If the fan can't keep up with what's coming from the cooler, the heated air stays in the case. The top fan should help that process. If the top is pulling too much air, then you get lesser air all the way through the cooler, more ends up bleeding out the top side, makes the cpu run hotter because of lack of efficiency.

With a downdraft type cooler, top fans are great, heat rises naturally, so air is moving in that direction anyways, added to by the gpu exhaust rising. A rear exhaust can often hinder that process as it's trying to pull that warm air 90° sideways.

With an aio, doesn't matter, air is being pushed to the corner anyway by the intake fans on the rad.

Case airflow is all about 1 thing, air Flow. What is it doing, where is it going, where isn't it going. Fan types play a major role there. Airflow/cfm fans move a Lot of air, but it doesn't go anywhere, it's air volume. Static pressure fans Move air a lot, smaller volume, more force. 3x LL's at front are pushing air to the gpu. This is a good thing. The AER in back is exhausting that air, doesn't need pressure, it needs to move volume.

Lowering volume moved, by adding the LL at exhaust might look good, but looks is not performance, the LL's just move a little, hard. But at exhaust, nobody cares how hard the air is or where it goes, it's outside the case.

2) The NF-P14 is a balanced fan. Less volume than the AER but stronger pressure. Excellent for intakes, ok for exhaust. At less than 100% it'll move @ the same air volume as the AER, close enough to make no difference. What will make a noise difference is the seperate header and adjusted fan curves. You'll want the LL at high rpm, @ 1200±, you'll only want the top exhaust at @ 900 rpm±. Regardless of AER or P14.

Personally, I'd go with Arctic F, just as quiet as either Noctua or AER, move the same amount of air, half the price.

 

[SilentMel0n]

1) depends on the cpu cooler. With a tower style cooler, air is drawn in the front and most of it is shoved out the back, right at the rear exhaust area, so a rear exhaust fan is somewhat important as far as directly pulling that hot cooler exhaust straight out of the case. If the fan can't keep up with what's coming from the cooler, the heated air stays in the case. The top fan should help that process. If the top is pulling too much air, then you get lesser air all the way through the cooler, more ends up bleeding out the top side, makes the cpu run hotter because of lack of efficiency.

With a downdraft type cooler, top fans are great, heat rises naturally, so air is moving in that direction anyways, added to by the gpu exhaust rising. A rear exhaust can often hinder that process as it's trying to pull that warm air 90° sideways.

With an aio, doesn't matter, air is being pushed to the corner anyway by the intake fans on the rad.

Case airflow is all about 1 thing, air Flow. What is it doing, where is it going, where isn't it going. Fan types play a major role there. Airflow/cfm fans move a Lot of air, but it doesn't go anywhere, it's air volume. Static pressure fans Move air a lot, smaller volume, more force. 3x LL's at front are pushing air to the gpu. This is a good thing. The AER in back is exhausting that air, doesn't need pressure, it needs to move volume.

Lowering volume moved, by adding the LL at exhaust might look good, but looks is not performance, the LL's just move a little, hard. But at exhaust, nobody cares how hard the air is or where it goes, it's outside the case.

2) The NF-P14 is a balanced fan. Less volume than the AER but stronger pressure. Excellent for intakes, ok for exhaust. At less than 100% it'll move @ the same air volume as the AER, close enough to make no difference. What will make a noise difference is the seperate header and adjusted fan curves. You'll want the LL at high rpm, @ 1200±, you'll only want the top exhaust at @ 900 rpm±. Regardless of AER or P14.

Personally, I'd go with Arctic F, just as quiet as either Noctua or AER, move the same amount of air, half the price.

Thank you so much.

When you mention the RPM's of the fans, (1200, 900) should this be when under load? Or idle?

 

[Karadjgne]

Load. That's what the curve does. At idle your fans will barely be moving, pwm will drop as low as 20%, which is @ 300rpm-400rpm. Any fan, even loud ones will be dead silent at that speed.

I have my fans capped at 900rpm by curve, they'll hit 1200rpm if I'd let them, but that's really mostly noise. Even then, they are extremely quiet.