BUILD Which 40mm Noctua Fan?

[wraith]

Hi All,

Appreciate this isn't quite FreeNAS related so apologies if this is in the wrong forum. Admin's, please feel free to move if necessary.

I recently purchased a SuperMicro 5018D-MTF server [c/w Microsoft Windows Server R2]. It is enclosed within a 813M-3 [1RU] chassis.

I'm looking at doing a little maintenance on the server including:

• Procuring some rails to place it within my rack;
• Replace the aging/crumpled air shroud, and;
• Whilst doing the above, replace the existing 40mm fans.

My query involves the fan replacements.

I'm currently considering a 40mm Noctua fans, having, generally, read good reports with this brand. I seem to have, broadly, the following two options:

• 5000 RPM [e.g. Noctua NF-A4x20 FLX];
• 4500 RPM [e.g. Noctua NF-A4x10 FLX]

I'm seeking some feedback/advice on whether the difference of 500 RPM is significant at the 40mm fan scale with regards to both cooling efficiency and noise. There isn't a significant price difference between the two, including the 5V and/or PWM variants on the above. Although only the 5000 RPM come with PWM.

At the moment the fans can, sometimes, get loud. However, the rack is based in my garage so isn't too much of an issue but something I'd to consider so I make the right purchase first time.

I'm still considering how I intend to use the new server in conjunction with my existing FreeNAS tower server. I'm contemplating setting up the WS2K12R2 server as a domain controller and redirecting the family's computers to work off the server [so always subject to redundancy and cloud backup]. I may run something like BOINC [which I've had some difficulty getting going in FreeNAS] which may push the processor and increase the volume of heat that goes with it.

Thanks all!

 

[Chris Moore]

I am not familiar with that model server, but you probably want to go with the lower RPM fan to keep the noise level down.

 

[tvsjr]

I'd suggest being careful. Rack-mount chassis rely on those fans to provide proper cooling, often using passive heatsinks on the CPU, controllers, etc. as well. You've talked about RPM, but you haven't talked about CFM nor static pressure.

You may also discover the chassis gets unhappy when it sees a fan that doesn't spin at the rate it expects.

 

[Chris Moore]

It is enclosed within a 813M-3 [1RU] chassis.

Excerpt from the chassis manual: https://www.supermicro.com/manuals/chassis/1U/SC813M.pdf

Code:

Fans:
the SC813M chassis includes three or four heavy-duty fans with open slots for two or
three additional fans if required. System fans for the SC813M chassis are powered
from the serverboard. These fans are 1U high and are powered by 4-pin connectors.

That being the situation, the system may not work properly if it isn't getting the correct feedback from the fans.

 

[wraith]

I am not familiar with that model server, but you probably want to go with the lower RPM fan to keep the noise level down.

Whoops, correct model should be 5018D-MTF! Thanks!

 

[wraith]

The SuperMicro specs for fans are [copied direct from website for the 5018D-MTF]:

• Total of five 4-pin fan headers supporting up to 5 fans
• 5x fans with tachometer status monitoring
• Status monitor for speed control
• Status monitor for on/off control
• Support 3-pin fans (w/o speed control)
• Low noise fan speed control
• Pulse Width Modulated (PWM) fan connector

Would I be correct in interpreting that:

• I don't need anything directly from SuperMicro;
• PWM is highly preferable, if not required.

With regards to voltage, the 5018D-MTF website states:

• Monitors for CPU Cores, +12V, +3.3V, +5V, +5V Standby, VBAT, HT, Memory, Chipset Voltages.
• 5-Phase-switching voltage regulator with auto-sense from 0.8375V-1.60V

Not sure how to interpret this as it relates to fans assuming it relates at all! There is a warning on the 5V spec that it can't be run at 12V. I'm interpreting to stay away from the 5V variant and stick with the following:
Noctua 40mm NF-A4x20 PWM 5000RPM Fan

These have LNA, can spin from 1200RPM - 5000RPM and can move between 8.3m3/hr - 9.4m3/hr. Noise is 14.9dB(A). Humans talk around 60dB so these sound pretty quiet. If I understand noise correctly [logarithmic scale], five fans should not push the dB rating much higher. This sounds ok...?

 

[tvsjr]

The fan used in that chassis is a FAN-0065L4: http://store.supermicro.com/featured-products/40mm-fan-0065l4.html#
Which is actually a Delta FFB0412SHN: http://www.delta.com.tw/product/cp/dcfans/download/pdf/FFB/FFB40x40x28mm.pdf

The Supermicro fan is 40x40x28, capable of up to 13,000RPM, providing 24CFM at 1.075inH2O (or 0.68m^3/min at 27.3mmH2O).
The Noctua fan you've chosen is 40x40x20 (so it's thinner). It tops out at 5,000RPM and provides 0.16m^3/min at 2.26mmH2O.

So, the fan you've chosen provides less than 25% the air flow at less than 10% of the static pressure. The static pressure is the killer... 1U chassis really rely on the fans forcing lots of air in to properly cool everything inside, much of which doesn't have fans of its own (no room to do so). Not only do you have to worry about cooling in the general sense, but you really need to be inspecting things with a thermal camera... with such a reduction in pressure and flow, you're going to start to see hot spots in the chassis.

You may also face issues from the fan speed monitoring in the Supermicro controller. There are ways to tweak this now, I believe.

Long story short - the fans you've chosen don't measure up. 4 of them don't equal 1 of the included fans. Supermicro chooses these fans for a reason, and uses PWM controls to slow the existing fans down when required. If you do decide to make this switch, I hope you know what you're doing, and have the proper equipment to determine if what you've chosen is working effectively. Heat is insidious... you might keep the CPU from simply shutting down, but what about all those other controllers? An overheated SATA controller can start throwing data errors during overheat, etc.

There's no such thing as a free lunch where fans are concerned. There are tricks that make fans somewhat quieter while delivering the same airflow at the same static pressure (which Noctua will have and Delta won't), but those tricks are good for a few dB - not 50dB.

 

[Chris Moore]

Whoops, correct model should be 5018D-MTF! Thanks!

I was able to find the system board in question based on that model number. It should have an X10SLM-F in it and that board is decent at regulating fan speed based on conditions. The fan header marked "FAN-A" is for the expansions card slots (A for Accessory). All the other fan headers are speed regulated based on the CPU temp.

https://www.supermicro.com/manuals/motherboard/C222/MNL-1428.pdf

 

[Chris Moore]

Whilst doing the above, replace the existing 40mm fans.

Is the reason you are replacing the fans just to make the system quiet?

 

[Chris Moore]

At the moment the fans can, sometimes, get loud. However, the rack is based in my garage so isn't too much of an issue but something I'd to consider so I make the right purchase first time.

PS. These systems are designed to be operated in a climate controlled environment. Typical data-centers would be kept within a few degrees of 20°C year round.

 

[wraith]

Is the reason you are replacing the fans just to make the system quiet?

Yes; Taking the opportunity whilst I have it out of the rack placing rails and installing a new air shroud.

 

[wraith]

Hi @tvsjr

Thanks for the educational tips and feedback; It has certainly given me something to contemplate. I'll be having some additional discussions with my the retailer :)

 

[Chris Moore]

Hi @tvsjr

Thanks for the educational tips and feedback; It has certainly given me something to contemplate. I'll be having some additional discussions with my the retailer :)

I tried slowing down the fans in my Supermicro servers and it worked fine as far as keeping the hard drives cool, the problem was keeping the CPU and other components cool. Like @tvsjr said, the CPU cooling solution in that chassis is a tiny, passive heatsink and it will probably not provide adequate cooling without massive amounts of air passing through it. I had to switch to active coolers in all the systems where I slowed the fan-wall fans.