SilverStone RM420 stock fans - replacement fans with adequate static pressure?

[punk]

If I replace the intake fans in my chassis, how high of a static pressure rating do I need to overcome the constraints of the chassis' HDD bays? Numerous Google searches have yielded no real helpful information. I wonder if it's not as simple an answer as I hope it is. I ran into similar issues quantifying what "high static pressure" meant when someone would make watercooling radiator fan suggestions - when comparing fan models, "high static pressure" would often be around 2.0 mmH2O compared to others at 0.5 or lower. Compared to a fan that can push 5 or 10 or 15 mmH2O, 2 mmH2O doesn't seem that high.
 
I have a SilverStone RM420 that comes with 4x DYNATRON / Top Motor 80x80x40mm PWM fans, P/N DF128038BH-PWM. They're rated for:

1000RPM (20%)	18.2 dBA	17.1 CFM	0.62 mmH2O
2500RPM (50%)	38.1 dBA	42.8 CFM	3.95 mmH2O
5000RPM (100%)	53.2 dBA	85.5 CFM	15.8 mmH2O

 

They're not running at 100%, but I'd be hard-pressed to guess where they're at. Fan control is via the SAS backplane's PWM fans and temperature sensor, so I can't tell the exact speed of the fans. I intend to leave them connected there for now since it allows me to regulate fan performance based on ambient temperature of the HDD bay in hardware. HDDs are around 35C idle and the fans provide enough airflow to keep my magma-hot LSI HBAs at round 50C.

 

I want to replace them with three 140mm fans to see if I can push the noise level down a little bit. I've seen quite a few posts about the Norco 4224 or similar where users replaced their fan wall with the 120mm variant (or the zip-tie variant), threw in some Noctua NF-F12s (or equivalents), and saw decent results both noise- and temperature-wise.

 

If I replace them with 3x Noctua NF-A14 PPC-3000s I'm sure I'd be close enough, but I'm curious whether or not I could get by with an PPC-2000 or even a normal NF-A14 and if it's possible to determine that without actually going out and buying all three types of fans, trying them all, and returning the rest. 😁

 

NF-A14 PPC-3000 PWM	3000RPM (100%)	41.3 dBA	158.5 CFM	10.52 mmH2O
NF-A14 PPC-2000 PWM	2000RPM (100%)	31.5 dBA	107.4 CFM	4.18 mmH2O
NF-A14 PWM		1500RPM (100%)	24.6 dBA	82.5 CFM	2.08 mmH2O

 

Thanks!

[LordShaaver]

Hi.

 

Did you ever replace the stock fans? I also have a SilverStone RM420 case and I replaced my stock fans with four Noctua 80mm fans (NF-A8 PWM). It works and the server is quiet, but in the summer for example the fans isn't quite enough.

If you replaced the fans, what modification did you have to do on the case to get the fans to fit?

 

Thanks!

[punk]

On 10/10/2019 at 11:51 PM, LordShaaver said:

Hi.

 

Did you ever replace the stock fans? I also have a SilverStone RM420 case and I replaced my stock fans with four Noctua 80mm fans (NF-A8 PWM). It works and the server is quiet, but in the summer for example the fans isn't quite enough.

If you replaced the fans, what modification did you have to do on the case to get the fans to fit?

 

Thanks!

 

I did, but I went a somewhat unconventional route. I designed and 3D printed a replacement fan shroud that holds three 140mm fans and populated it with Noctua NF-A14 PPC-3000 PWM fans. The setup seemed to work well. The 8x 15K SAS HDDs I had installed hovered around 35C-38C with low to moderate use, which remained GREEN on UnRAIDs dashboard temperature-wise. The SSDs that were installed were inconsequential.  The room its in is around 23C. Unfortunately, the server is torn down / offline at the moment for an unrelated rebuild, so I'm unable to pull CPU temps, etc.

 

Noise-wise they remained audible at all times, but it was a low background hum that was almost unnoticeable. In fact, I didn't realize how used to them I was until I shut the server off ... the office is creepy quiet, and the white noise from the fans really helped drown out neighbors, etc.

 

The NF-A8s are far too wimpy, unfortunately. 😞

 

What I've found interesting is the different fans that different server/case manufacturers build into their chassis. It makes me curious where their data comes from, what kind of tests they perform, what they design for, etc. For example, a 2U Supermicro box that I'm working on right now has 4x 80mm fans up front that are 11,000 RPM, 116 CFM, 54.3 mmH2O, 62.5 dBA monsters - for a 2U box with 12 drives. Meanwhile, the 4U UnRAID box I built with the same specs (same CPUs, same RAM, etc.) came with four 80mm fans with the specs in my original post.

 

EDIT: Both CPUs were actively cooled in my RM430 as well, which helped the Noctua fans pass muster.

Edited December 13, 2019 by punk

[altano]

Hey, could you share that shroud 3d model? I have the same case and would be interested in your mod...

[LordShaaver]

Hi again. I would also be interested in that shroud 3D model if possible. 🙂