Connecting a buttload of fans to a single header

myoung

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If I understand this reference correctly I should connect my CPU and exhaust fans to FAN1-4 headers and my fanwall to FANA header. I have enough y-cables to connect all of them to FANA, but should I worry about driving 3x 120mm fans from a single header? I don't want to pull to much current and melt something on the motherboard.

Mainboard: Supermicro X9SRL-F
Chassis: Norco RPC-4224
Fans: Fanwall - 3x Noctua NF-F12 PWM, CPU cooler - 2x NF-B9 PWM, Exhaust fans - 2x Unlabeled 80mm 3-pin
 

Ericloewe

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Supermicro claims that the headers are good for 2.5 A. If Noctua's spec for the NF-F12 is even close to reality, you could easily connect ten of them to a single header with no sweat.
 

jgreco

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The fan headers do have ratings that are available in the manual. However, you should not drive multiple fans from a single header, even if the power ratings look sufficient to handle it, because a stalled fan on a heavily loaded header can cause a large current draw and ruin the control circuitry, burn out PCB traces, etc.

If you wish to control multiple PWM fans, connect them to the server power supply directly, and create a Y that is only for the PWM signal. This arrangement is available prebuilt but you have to look a bit harder for it

https://www.amazon.com/Splitter-Molex-headers-CONNECT-MULTIPLE/dp/B009D3HV1Q

Most people are lazy and use the crappy Y cables that do not properly source power from the PSU.

Also, make sure all fans connected to the mainboard are PWM - do not mix 3-wire and 4-wire fans.
 

jgreco

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Supermicro claims that the headers are good for 2.5 A. If Noctua's spec for the NF-F12 is even close to reality, you could easily connect ten of them to a single header with no sweat.

What's the stall current on the NF-F12?
 

jgreco

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Fanwall - 3x Noctua NF-F12 PWM

Also, I can't imagine that these are anywhere near acceptable in terms of the static pressure necessary to properly cool a 24-drive-in-4U chassis. Creating an appropriate pressure differential typically requires a lot of power. You are trying to force air through the tiny gaps between the drives and the trays, and if you fail to do that well, the drives cook, which is an expensive lesson in server design and engineering.
 

myoung

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Wow, thanks for all the input!

How do I quote another user? i.e jgreco said:

Supermicro claims that the headers are good for 2.5 A.

This is good to know, I didn't read anything about it in the manual.

If you wish to control multiple PWM fans, connect them to the server power supply directly, and create a Y that is only for the PWM signal. This arrangement is available prebuilt but you have to look a bit harder for it

https://www.amazon.com/Splitter-Molex-headers-CONNECT-MULTIPLE/dp/B009D3HV1Q

This seems like a good idea, I'll probably get one.

Also, make sure all fans connected to the mainboard are PWM - do not mix 3-wire and 4-wire fans.

I've disconnected the exhaust fans for now then. The manual says that FAN1-3 are 3-pin compatible, whats the reasoning for not mixing 3-pin and 4-pin?

Also, I can't imagine that these are anywhere near acceptable in terms of the static pressure necessary to properly cool a 24-drive-in-4U chassis. Creating an appropriate pressure differential typically requires a lot of power. You are trying to force air through the tiny gaps between the drives and the trays, and if you fail to do that well, the drives cook, which is an expensive lesson in server design and engineering.

Are there any references/ guidelines you can recommend for how to get the right size fans or is it just P=plenty?
 
Last edited:

Ericloewe

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What's the stall current on the NF-F12?
They claim 50 mA maximum, which seems optimistic as hell to me.

How do I quote another user?
Highlight the text and press the little button that appears, or use the reply button to quote the whole message.
 

jgreco

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I've disconnected the exhaust fans for now then. The manual says that FAN1-3 are 3-pin compatible, whats the reasoning for not mixing 3-pin and 4-pin?

PWM fans are driven with 12V and a pulse width modulation on the 4th wire. 3-pin fans are speed-controlled by varying the fan voltage. This is handled by the BMC, and evolving technology over the years means you need to be a little cautious. Some boards do an automatic probing to determine if PWM is available. This works by trying PWM fan control and watching tachy for change in status. The trick is that some boards only do this on a single fan, meaning that if you mix fans, you can get bad results. The specifics of this have varied over the years and even depending on the particular board sometimes.

I dug up the X9SRL manual and it appears that it is PWM-drive only, which means that your 3-wire fans can be safely connected, but will always run at full speed. If you got those gimpy Noctuas for the fan bulkhead, I assume you're trying to build a "quiet" server, so you'll end up replacing the exhaust fans anyways because you'll find them running at full speed, and then want to drive them with PWM. Just a guess.

Are there any references/ guidelines you can recommend for how to get the right size fans or is it just P=plenty?

I'm not trying to be snarky, nasty, judgmental, etc., here, just want to convey the situation and information as I see it, being clear. The possibility of doing significant damage to a large array of expensive HDD's by cooking them bothers me.

We semi-frequently see people post about converting a 2U-12bay or 4U-24bay server chassis to FreeNAS and they want to use it at home. Whether it is because they're used to consumer PC's and have drunk the "silent PC" kool-aid or because they've seen some doofus do it on YouTube/blog/etc, quite often they want to "silence" the noisy screechy (all accurate) evil server grade fans by replacing them with wimpy "silent" fans.

Silencing a NAS is TOTALLY possible. You just need the right chassis. Or a trick strategy, But these 24-bay chassis were designed for data center use and are not a good starting point. You CAN run 12 drives, staggered, in a 24 bay rack chassis, replacing all the fans with quiet ones, and come out with a successful quiet server. The reason this works is because you have 12 open bays allowing easy airflow by the remaining drives, carrying away heat. Totally works. The moment you add the 13th drive, you get a hot spot though. You're really better off with a non-rackmount chassis that just has great airflow.

Supermicro uses some beefy 7K RPM fans, their part# is FAN-0127L4, an 80mm x 38mm thick fan, often a Nidec V80E12BHA5-57. Three of these make up the fan bulkhead. Nidec lists these as 7.2W fans with static pressure of 270 Pa. Generating static pressure differentials tends to chew energy because of the work involved.

Now the bad news. We don't have much experience with the Norco's here. In the early days of this forum, we saw some of them come through, often with bad choices having been made. I've been pushing people towards the Supermicros because the solution was designed by a professional server design engineer and it is known to work. I can tell you that users have found the 120MM Norco fan bulkhead is the more challenging option. Their 80MM fan bulkhead is a better choice because you'll have a larger number of fans to pick from that are suitable.

Typically you would need a manometer and a full array of sacrificial drives to act as a dummy heat load/temperature sensors to measure how effectively a given combination of bulkhead/fans is actually working.

I don't have a magic suggestion for you. This is a complex multivariable problem. Cooling isn't as hard if you're using 5400/5900RPM drives instead of 10K/15KRPM drives, if you are running the server in a cool environment, etc. I'm sorry I can't give you a more directly helpful answer. Best I can do is let you know about the potential sharp edges.
 

Stevie_1der

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Supermicro uses some beefy 7K RPM fans, their part# is FAN-0127L4, an 80mm x 38mm thick fan, often a Nidec V80E12BHA5-57. Three of these make up the fan bulkhead. Nidec lists these as 7.2W fans with static pressure of 270 Pa. Generating static pressure differentials tends to chew energy because of the work involved.
And now for comparison some Noctua models:
The NF-F12 industrialPPC-3000 PWM (their beefiest 120mm type) is listed with 7.63 mm H2O, that should be 75 Pa.
The NF-A14 industrialPPC-3000 PWM (their beefiest 140mm type) is listed with 10.52 mm H2O, or 103 Pa.
The NF-F12 PWM is listed with 2,61 mm H2O, or 25.5 Pa.

I knew there had to be a reason for these turbines installed in rackmount chassis, but I've never actually compared the numbers until now...
 

myoung

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I'm not trying to be snarky, nasty, judgmental, etc., here, just want to convey the situation and information as I see it, being clear. The possibility of doing significant damage to a large array of expensive HDD's by cooking them bothers me.

We semi-frequently see people post about converting a 2U-12bay or 4U-24bay server chassis to FreeNAS and they want to use it at home. Whether it is because they're used to consumer PC's and have drunk the "silent PC" kool-aid or because they've seen some doofus do it on YouTube/blog/etc, quite often they want to "silence" the noisy screechy (all accurate) evil server grade fans by replacing them with wimpy "silent" fans.

Silencing a NAS is TOTALLY possible. You just need the right chassis. Or a trick strategy, But these 24-bay chassis were designed for data center use and are not a good starting point. You CAN run 12 drives, staggered, in a 24 bay rack chassis, replacing all the fans with quiet ones, and come out with a successful quiet server. The reason this works is because you have 12 open bays allowing easy airflow by the remaining drives, carrying away heat. Totally works. The moment you add the 13th drive, you get a hot spot though. You're really better off with a non-rackmount chassis that just has great airflow.

Supermicro uses some beefy 7K RPM fans, their part# is FAN-0127L4, an 80mm x 38mm thick fan, often a Nidec V80E12BHA5-57. Three of these make up the fan bulkhead. Nidec lists these as 7.2W fans with static pressure of 270 Pa. Generating static pressure differentials tends to chew energy because of the work involved.

Now the bad news. We don't have much experience with the Norco's here. In the early days of this forum, we saw some of them come through, often with bad choices having been made. I've been pushing people towards the Supermicros because the solution was designed by a professional server design engineer and it is known to work. I can tell you that users have found the 120MM Norco fan bulkhead is the more challenging option. Their 80MM fan bulkhead is a better choice because you'll have a larger number of fans to pick from that are suitable.

Typically you would need a manometer and a full array of sacrificial drives to act as a dummy heat load/temperature sensors to measure how effectively a given combination of bulkhead/fans is actually working.

I don't have a magic suggestion for you. This is a complex multivariable problem. Cooling isn't as hard if you're using 5400/5900RPM drives instead of 10K/15KRPM drives, if you are running the server in a cool environment, etc. I'm sorry I can't give you a more directly helpful answer. Best I can do is let you know about the potential sharp edges.

Thanks for the detailed response, I never assumed you were being snarky. I'm not married to the idea of a silent NAS, I bought this system used and it came with these fans (minus the 80mm fans which I had lying around, inspiring this post in the first place.)

Right now there are only 8 HDD + 2 SSD in the chassis, so if I space them out these fans should be good for now. I will probably get some stronger 4-pin 80mm exhaust fans and one of the y-cables you listed above. I'll set a low threshold on the drive temp alerts and if they get too high, I'll look into some stronger fans.

I also have a H310 HBA in this system. I've seen a few posts saying these can easily overheat and lead to issues. Is there a way to monitor HBA temperature?
 

jgreco

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I never assumed you were being snarky.

People sometimes mistake my information-dense and blunt replies..

also have a H310 HBA in this system. I've seen a few posts saying these can easily overheat and lead to issues. Is there a way to monitor HBA temperature?

Sadly, no. Well yes if you rig something yourself, but nothing built in. These do not "easily" overheat, at least in my opinion, but you do need to have some airflow over them. If you put one in the bottom slot of a tower chassis and there's no way for air to flow over the fins easily, they tend to go all WOPR on you. This is unfortunate as they're good controllers. The natural front-to-back airflow in servers normally takes care of that.
 

myoung

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The natural front-to-back airflow in servers normally takes care of that.

Good. It's in the middle of the case, so as long as the drives stay cool the HBA should be fine.

Thanks for guiding me deep into a rabbit hole I didn't even know existed:). I'm sure I'll be back later with more questions
 

jgreco

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Good. It's in the middle of the case, so as long as the drives stay cool the HBA should be fine.

And that's why it is really not a problem in servers.

Thanks for guiding me deep into a rabbit hole I didn't even know existed:).

Well, we like happy outcomes, which are really only possible when people say something that clues us in to a potential issue. If you hadn't asked about fan headers, ...

I'm sure I'll be back later with more questions

;-)
 
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