Supermicro PWS-920P-SQ Temperature

revengineer

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Hi,
I have a Supermicro Chassis SC846 CSE-846E16-R1200B and I have replaced the power supplies with PWS-920P-SQ. Everything is working fine but I just noticed touching the inside wall facing the power supplies that it was hot to the touch despite the server being off for ~24 hours. So I installed IPMIview to read the temperatures of the PMBus and they read 45C and 59C for Temperatures 1 and 2, respectively, for Power Supply 1 and 43C and 61C for Temperatures 1 and 2, respectively, for Power Supply 2. The temperatures actually do not change much when the server is on and draws ~250W. The idle temperature seems hot and I was wondering if this is normal.

Feedback appreciates!

Thank you.
 

Samuel Tai

Never underestimate your own stupidity
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You're seeing the inlet and outlet temps of the power supplies. The internal temp inside the chassis is around 45C, and the temp of the power supply exhaust is around 60C. Your chassis may not have enough free space behind the power supplies to properly dissipate that exhaust, and it's blasting the drywall. Your chassis internal temperature is also pretty warm.
 

revengineer

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The 45C for the inside of the chassis is about right when the server is running. I just do not understand why the power supplies get so warm when the server is off, only the baseboard processor is running. Below is the complete dataset for this state.

1591315017501.png
 

Samuel Tai

Never underestimate your own stupidity
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That's because power supplies still need to dissipate their internal transformers and AC/DC converters.
 

revengineer

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OK, thank you. I take it that the behavior is normal but understand that the chassis temperature is somewhat elevated. I have my equipment in close rack with fan control. The fans keep the temperature near the top of the rack to <35C. The Supermicro FreeNAS server is toward the bottom where it is somewhat cooler. So chassis temperatures in the 40+C range do not surprise me. All my temps are including HDDs are <50C so I think I am still in an ok range. The alternative is to have the rack fans blowing constantly which is somewhat annoying.
 

revengineer

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To make sure that I do not cause damage in the long run, I ran the temperatures by Supermicro support. They confirmed that they are in the normal range. By design, the power supplies use the aluminum housing and by extension the chassis as heat sinks. So to fact that the chassis wall is warm to the touch is normal as well.
 

subhuman

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I just do not understand why the power supplies get so warm when the server is off, only the baseboard processor is running. Below is the complete dataset for this state.
I know this was already answered, but the data you posted has the answer.
PS 2 input 116v/.18, both fans RPM 0
The power supply has to dissipate 20W with only passive cooling. It will be quite a bit above ambient temperature.
 

revengineer

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Makes sense now. I underestimated the heat generated by 20W dissipation.
 
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