How to choose the right fans for Server

[Nothanksss]

Hi, i have an Supermicro cse-829u. The fans are really loud so i want to replace them. I searched on the internet but i didnt really find anything. The heatsinks have rougthly 16 fins per inch (fpi). I read that i would need a higher air pressure with a higher fin density, but other than what chatgpt told me i couldnt find any good information on this. Chatgpt said the fans with an air pressure over 4 mmH₂O would be good but i dont know if i can trust this information. I also dont know what cfm numbers i should look for. I found these fans: https://eu.mouser.com/ProductDetail/Sunon/MF80252V1-1000U-A99?qs=EU6FO9ffTwdxqmoWFZ03vg== that have an cfm of 41 and 4.572mmH₂O. The are pretty cheap and only spin up to 3200 rpm and are pretty quiet with just 33db. I also dont know if this brand is any good.
Id appreciate anny help

 

[nexox]

We probably need to know what you're cooling (single or dual CPU of what TDP, how many of what sort of drives, any PCIe cards that run hot.) I've had good results (in an 826 chassis, pretty similar as far as cooling goes) with a relatively low TDP CPU and an active 2U heatsink with the fan swapped for a 60mm Noctua, combined with either Arctic P8 Max fans or their s8038 7k, the latter is a bit louder at idle but moves more air and has way more headroom when things get warm.

 

[Nothanksss]

As of now its basically just a nas, so 9 hdds and an hba. Im running two of the Intel(R) Xeon(R) CPU E5-2620 v3 @ 2.40GHz for an combined tdp of 170w (85w each). I'll probably add a mellanox connect-x 3 or something simmelar a some point and maybe upgrade the cpu for a fev more cores and a higher single core performance. I'm also thinking of adding an gpu to the machine for running some llms. Something like the radeon instinct mi50 which does have a pretty high tdp at 300w. So i want to have some headroom for upgrades but my number one priority is being able to run it without going deaf.

 

[Whaaat]

I'm also thinking of adding an gpu to the machine for running some llms. Something like the radeon instinct mi50 which does have a pretty high tdp at 300w.

LOL, you'll need a 38mm thick fan running at 12k rpm to cope with this thing alone, your slim&silent 3200rpm fans will be completely useless taking into account that front intake is almost completely filled with HDDs

 

[nexox]

Without the GPU you can probably get away with Arctic P8 Max fans, might get borderline with higher TDP CPUs, or at least the fans might constantly run fast enough to make more noise than the S8038 7k. Whatever you do make sure to monitor the various temperatures under full load after swapping to ensure there's sufficient airflow everywhere.

 

[louie1961]

That's a whole of of CPU power and TDP just for a NAS. Would you be opposed to moving to a different case? I think your plans are incompatible with a 2U case. I just rebuilt my server that was in a Fractal Designs Node 304 into a 4U case so I could add a GPU etc. My new setup has a Ryzen 7 5800XT CPU (reputation for running very hot) as well as a LSI 9300-81, Mellanox ConnectX3, a RTX 2000 ADA GPU, nine SATA SSDs and two NVME drives. I replaced the case fans with Noctua fans (two 120 mm fans front and two 80mm fans in the rear) and threw a NH-D12L CPU cooler on it. It is whisper quiet at idle and idle cpu temps are around 36-37 degrees.

 

[Nothanksss]

So, im thinking of buying the arctic s8038 7k. I experimented with some ipmi fan control yesterday and was able to significantly reduce the noise without the cpu temp getting too toasty. But it was still clearly audible. I set the fan speed too a minimum of 20% from where it scales linearly. As to rebuilding the nas, i dont think thats a viable option for me. I bought this server because it was pretty cheap and could house up to 12 3.5 inch disks. If i were to build something myself i would probably be looking at a price point of at least 1000 bucks for something nicer, as far as i remember, which for me is pretty expensive.

 

[nexox]

You're not going to get that chassis inaudible unless you remove most of the disks and switch to modded active CPU heatsinks, you may also need to replace the PSUs, depending on which model you have. You'll be better off moving the system somewhere you can't hear it.

The S8038 7ks certainly aren't silent even at low speed, the P8 Max is quieter, but probably don't provide as much cooling at 20% as the current fans.

 

[kapone]

Using 3.5" spinners? - Check
Chassis almost full of disks? - Check...almost
Using a 2U chassis? Check

Want it to be quiet? - Check - Fu^%$#@!
Want to add even more hardware? - Check - Fu^%$#@!
Want "headroom" for even more upgrades? - Check - Fu^%$#@!

Yeah, that's not going to happen. Pardon my slightly sharp tone, but if you browse just this forum (not even counting countless others outside STH) for a few hours, you'll realize this is a fool's errand. Can't be done.

Not enough static pressure and airflow = disks will cook, and potentially other hardware as well (like the GPU you're thinking of)
Enough static pressure and airflow = Aint gonna be quiet. There's just no way around this.

My advice? Keep that 2U server as pure storage only, which requires very little CPU. Just an HBA and NIC. That's it, nothing else. That may end up being an acceptable acoustic/thermal envelope, with slower/aftermarket fans or even IPMI slowing down stock fans.

Build another machine for compute.

 

[louie1961]

And if you do keep it as is, take out one of the CPUs. You don't need that much horsepower for a NAS.

 

[twin_savage]

FWIW I'm going through something similar on a RM437 case; I came the conclusion that 25mm thick fans weren't appropriate for the very restrictive parts of the case, but I could get away with them in the upper chamber of the case since it only had to pull air through 12 HDDs; however the 80x25mm fans I chose for this part of the case had twice the static pressure as those mentioned in the first post.

 

[Nothanksss]

Ok, so just use the box as a NAS. As i said im currently running the fans at 20% and the cpu tems are pretty stable at ca. 32C. As i understand it, the lower the rpm the higher the air pressure but lower air throughput. So would it be viable to set it to something like 15 or even 10% fan speed? If so i'd problay just keep the fans stock. Otherwise i'd probably just replace the fans with the S8038 7ks's seeing as they are cheaper for a 4 pack and as nexox said, would probably spinn slower as the P8 Max's making them not that much different in noise. I also don't need it whisper quiet, just so that i can sleep. Worst case, i'll just have to get used to it LOL. Thanks to everyone for the input

 

[nexox]

Lowering the RPM with IPMI lowers both pressure and flow, for a given RPM of a specific fan more static pressure (ie resistance to air moving) means less flow, some fans do better than others at various parts of that curve and make more or less noise while they're doing it. Keep in mind your CPUs could be 32C and your drives could be 55C, check everything.

 

[kapone]

check everything

exactly. CPU temp is just one thing. Active CPU coolers can keep that in check while the drives keep getting toasty.

 

[Nothanksss]

the drives are all around 27 to 32C so thats also seems ok

 

[twin_savage]

the drives are all around 27 to 32C so thats also seems ok

Do you have a SAS expander on your backplane? For me that was the hardest thing to properly cool while reducing fan speeds.

 

[Nothanksss]

I think so, where can i see the temp of the chip? It doesn't show under temp sensors in the Supermicro management utility.

 

[twin_savage]

I think so, where can i see the temp of the chip? It doesn't show under temp sensors in the Supermicro management utility.

For mine I had to log into my raid card's dedicated IPMI to view the temperature. lm-sensors might also show the temperature but I'm not sure.