Supermicro PWS-1K21P-1R, PWS-501P-1R, PWS-920P-SQ noise comparison

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OutOfSync

New Member
Feb 24, 2016
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Bremen, Germany
Hey guys, I just bought a Supermicro SC836 chassis that came with redundant 1K2 gold powersupplies (UK Dell Compellent SC40 server deal). Since the server will be sitting in my office, I was trying to find a less noisy power supply. This will only be a backup storage server so redundant power is not very important and I certainly don't need 1200W to spin a few harddrives.

I found some information but it was not really enough for me to make a decision - so I decided to test myself. I just ordered both PWS-501P-1R and a PWS-920P-SQ power supplies for comparison with the PWS-1K21P-1R. Thanks to our consumer-friendly regulations in Germany I have two weeks for noise comparison before one of the supplies will go back. I thought I share the results with you.

Test setup:
  • SC836 with SM X8DTH-iF mainboard, 6GB ECC RAM and Xeon E5540
  • All fans removed to reduce background noise
  • Only one power supply tested at a time, no redundancy
  • Record noise for 10s using Behringer ECM8000 microphone and RME Fireface, distance mic to PWS ca. 30 cm
  • Idle (only IPMI active) and loaded BIOS setup screen
  • Report PSU monitoring values and spectrum analyzer (Audacity)

PWS-1K2P-1R:

This power supply is clearly the loudest, even when just plugged in and the computer is not powered up, the fan spins up and it is very audible. When the system is powered on, the fans spin up even more and they stabilize somewhat during the BIOS setup screen. However, the fan speed varies a bit and it goes up and down ~1000 rpm which is really annoying.
Monitoring numbers:
Idle, no power: fan 3000 rpm, 16W input power (probably just the fan spinning + IPMI services)
BIOS, system powered on: 4200-5600 rpm, 120-130 W input power
1K2-spectrum.png


PWS-501P-1R:
Much more quiet power supply, although the fan still spins up when it is plugged in and and the computer is still powered off. But much less annoying than the 1200W PWS. The fan seems to be constant around 4000 rpm no matter if plugged in or in BIOS setup screen, it spins up a bit while the temperature rises however nothing too dramatic.
Monitoring numbers:
Idle, no power: fan 4000 rpm, 8 W input power (fan spinning, IPMI services)
BIOS, system powered on: 3950-4250 rpm, 113W input power
501P-spectrum.png


PWS-920P-SQ:
What a relief, no fan spinning when it is just plugged in. When powered on, the fan goes up to 2000 rpm and it just stays there. I have not seen it any higher in my low-power configuration.
Monitoring numbers:
Idle, no power: no fan, 1W input power (mainboard IPMI)
BIOS, system powered on: 2050-2100 rpm, 112W input power
920SQ-spectrum.png


The three power supplies fall into two loudness categories: the 1K2 gold is clearly the loudest and the 500W and 920W are much more comfortable. The spectrum analyzer results can be directly compared on a relative level (absolute dB numbers are not comparable to official SM numbers found in this forum) since the test setup was always exactly the same and the microphone was not moved. I have attached the WAV files so that you can listen to the differences if you want to know the details.

The 500W will go back to the shop and the 1K2 gold will find a new home in an environment where noise does not matter. I will very happily keep the 920SQ, it is a really great PWS. What a difference!
 

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canta

Well-Known Member
Nov 26, 2014
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fan RPM depends on load and internal temperature.
501 is quite when loading below 40% from rated Watts, assuming normall room temperature. yeah fan is running when power is off(3K-3,5K RPM on mine). I have two models that haave different fans, one nidec, and the other one is san ace. san ace running more RPM ~500-800 *my observation via IPMI tools

SQ is quite when power off (no running fan). it will ramps up in rpm, I believe the rated max RPM is 10K; due on temperature and loading consumption.

you need to incluede load wattage to be honest :D.
my rule of thumb, never loaded more than 40% of rated watts.
 

OutOfSync

New Member
Feb 24, 2016
5
15
3
Bremen, Germany
You are right, I will prepare some more tests with higher load. I have to think about the best way to use more power without generating too much additional fan noise besides the power supply.
 

Kristian

Active Member
Jun 1, 2013
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PWS-920P-SQ:
What a relief, no fan spinning when it is just plugged in. When powered on, the fan goes up to 2000 rpm and it just stays there. I have not seen it any higher in my low-power configuration.
Monitoring numbers:
Idle, no power: no fan, 1W input power (mainboard IPMI)
BIOS, system powered on: 2050-2100 rpm, 112W input power
View attachment 1702

I am using a Supermicro X10-SLH-F with a 920P-SQ PSU and with idle, no power: Fans are at zero RPM, but with mainboard IPMI I see 10,56W using a Kill-a-watt and 20w when looking in the IPMI GUI under power source.

Is there anything I could do to get somewhere near this 1w that OutOfSync has archived?
I am a bit lost here and trying to get my electricity bill down as good as possible (yeah 9W is not a high number to save)
 

Laugh|nGMan

Member
Nov 27, 2012
37
7
8
I am using Supermicro X9SRL-F ipmi is ON with fanless SeaSonic Platinum Series SS-400FL2 PSU. Using UBiQUiTi mFi mPower as watt monitoring device I see 3.5-3.7W, so i don't believe that SM 920W psu dated from 2009 can suck only 1W. IMHO that's bullshit :)
 
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canta

Well-Known Member
Nov 26, 2014
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I am using Supermicro X9SRL-F ipmi is ON with fanless SeaSonic Platinum Series SS-400FL2 PSU. Using UBiQUiTi mFi mPower as watt monitoring device I see 3.5-3.7W, so i don't believe that SM 920W psu dated from 2009 can suck only 1W. IMHO that's bullshit :)
500W Platinum PSU on mine is sucking 4W when is off by monitoring directly to ac line:p...
why? the PSU fans is spinning low...

for non spinning fan in 920 SQ,,, 1Wto 2W is doable, by assuming fan is not spinning. this is my understanding.
 

canta

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Nov 26, 2014
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I am using a Supermicro X10-SLH-F with a 920P-SQ PSU and with idle, no power: Fans are at zero RPM, but with mainboard IPMI I see 10,56W using a Kill-a-watt and 20w when looking in the IPMI GUI under power source.

Is there anything I could do to get somewhere near this 1w that OutOfSync has archived?
I am a bit lost here and trying to get my electricity bill down as good as possible (yeah 9W is not a high number to save)
10W when is off? this is away too much :D, if the psu fan is off......
I assume that you are monitoring from AC line..

my 500 platinum takes 4W when is off, the psu fan is running on low speed.
the consumption during off is depending on psu fan. that PSU fan is good on pulling much amps.
 

Laugh|nGMan

Member
Nov 27, 2012
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I just want to point out that mine SeaSonic Platinum Series SS-400FL2 PSU is fanless. And sits in different sm case (SC742) with x9srl-f.

Few years ago i have chance to test Cooler Master VS Series V450S (RS450-AMAAG1-EU). This psu for IPMI ON showed zero differences at such a low loads compared to SeaSonic SS-400FL2. Same load at outlet 3.5-3.7W maybe +/- 0.1W
Despite my hopes, because some tests on internet showed little better efficiency on low loads, but i gained nothing :)
 

canta

Well-Known Member
Nov 26, 2014
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I just want to point out that mine SeaSonic Platinum Series SS-400FL2 PSU is fanless. And sits in different sm case (SC742) with x9srl-f.

Few years ago i have chance to test Cooler Master VS Series V450S (RS450-AMAAG1-EU). This psu for IPMI ON showed zero differences at such a low loads compared to SeaSonic SS-400FL2. Same load at outlet 3.5-3.7W maybe +/- 0.1W
Despite my hopes, because some tests on internet showed little better efficiency on low loads, but i gained nothing :)
speaking on hot-swapable server PSU :)..
non running fan during idle should eat less power on current/4 yers good PSU.

I was in shock when seeing 4-5W on 500W platinum PSU with running low RPM PSU fan, since 1000W gold psu consumed 10W with running low RPM PSU fan.



this is me only:
honestly, I never trus fanless PSU, something happens.. no way to cool the psu directly.
on other scenario on non fanless PSU, the fan will speed up and run in full speed :D.
 

PigLover

Moderator
Jan 26, 2011
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The SQ model is not fan less. But it is smart enough to turn off the fan completely when it is not needed.

Sent from my SM-G925V using Tapatalk
 

Kristian

Active Member
Jun 1, 2013
347
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10W when is off? this is away too much :D, if the psu fan is off......
I assume that you are monitoring from AC line..
The PSU Fan is off and I am monitoring from a Kill-a-watt and a mFi Pro. Both are showing 10.x watts when the computer is switched off.
 

Fritz

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Apr 6, 2015
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I'm using a PWS-1K28P-SQ in my CSE-745TQ. It's sitting right next to me. I can hear it but it's quiet enough not to be annoying. I've had other desktops that were louder.
 
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JoeB

New Member
Jul 31, 2016
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I'm a few years late, but thank you for the work you put into this. Your effort has made my office life more comfortable.

I built a custom enclosure that holds a Supermicro 1U SC808 chassis with dual X8DTT-F motherboards vertically against the wall on the desk in my home office. The top of the server has been removed. Four 140mm high-static pressure fans are mounted on the front of the enclosure directly over the CPUs and RAM.

I knew removing the 6 1U screamers and replacing them with the quite 144mm fans would help a lot with noise, but was disappointed in the noise generated by the stock PWS-1K21P-1R (1200W) power supply. It certainly wasn't ear splitting, just annoying.

After checking with Supermicro support, I replaced the PWS-1K21P-1R with a PWS-920P-SQ (920W). Now all I hear is the soft whoosh of the four 140mm fans. Temperatures inside the enclosure are 35°C to 40°C
 
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