Resolved The operating temperature is 50°C, but the fan will not start unless 55°C has been reached.

SilverStone Technology Co., Ltd.- ST30SF
I have bought V1.0, which has a fanless mode. According to the above product page, the maximum operating temperature is 50°C, and the fan will not start unless the temperature has reached 55℃.
So, is 55℃ acceptable when the PSU is designed to work at 50℃? Will 55℃ shorten the life of the PSU over time?
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The above discrepancy also exists in the following PSU:
SilverStone Technology Co., Ltd.- SX600-G
The maximum operating temperature is 40°C, and the fan will not start unless the temperature has reached 45℃.
Is there a reason to justify the discrepancy?

 

No where does it say that is the "maximum" operating temperature allowed. What that means is those supplies are fully capable of maintaining that full output within specified efficiency and voltage tolerances at those temps. 50°C is not hot enough to cause any damage or affect the expected life span of the power supply.

Note those are considered the "normal" operating temperature ranges. So it make sense for a supply designed for silent and low noise operation to not activate the fan until those temps are exceeded. The fact the fan does turn on at 55°C tells me all is working just fine!

SilverStone has a long standing reputation of making quality, reliable power supplies. IMO, you made a good choice and I would enjoy the silence!

In the meantime, make sure your CPU temps remain decent too. And if necessary, consider adding another case fan to your system and that should help keep the PSU's temp down too.

 

It says "Operating temperature 10°C ~ 50°C (V1.0)". Can 50°C be seen as the maximum?
The moderator below had made some worrying comments, so I asked the same question here.
Is 55℃ acceptable to a PSU? - Components - Tom's Hardware

Also, I found the following "80 Plus Gold" PSU featuring "ECO Mode", where the fan starts at 55°C too.
www.evga.com/products/Product.aspx?pn=210-GQ-0850-V1 EVGA 850 GQ
www.evga.com/support/faq/afmviewfaq.aspx?faqid=59433 ECO Thermal Control System

 

http://www.silverstonetek.com/sstedm/st30sf/EN-ST30SF.pdf
http://www.silverstonetek.com/downloads/Manual/power/EN-ST30SF-Manual.pdf
SilverStone is a Taiwanese company. I wonder why Chinese versions are unavailable. (I am Chinese.)

 

Is it possible for the fan to start at 40% loading according to the blue line?
It seems that the RPM is 1588 when the loading is over 100% (overloading).

 

I am sticking with what I said. You are getting yourself worked up over nothing!

The moderator is right - but he worded his reply poorly. 55° is too hot for the PSU. That's exactly why the fan turned on like it is supposed to - to keep it from getting hotter.

BUT it is NOT so hot that it will cause damage. Thermal protection circuits will cause the PSU to shutdown completely long before any damage to itself or the connected devices occurs.

By too hot, that simply means the PSU cannot guarantee the output voltages will be properly regulated to maintain the required +3.3VDC, +5VDC and +12VDC voltage within the maximum allowed ±5% tolerances and/or at the maximum specified wattage/efficiency.

Too hot does NOT mean it is about to burn up or catch fire.

If 55°C was anywhere near damaging temperatures, those power supply makers would design the supplies so the fans would spin up long before it came anywhere near 55°C. But then you and other consumers might be complaining that their power supply fans are making too much noise!

 

I don't mean causing instant damage or even a fire.
I mean shortening the life of the PSU over time.

I am not working myself up.
I am just interested to know more about it.
I saw the following sentence elsewhere. Do you agree with it?
"I read that every 1c increase from the continuous rated temperature is about 10 less watts"

 

Sorry for my stubbornness, but I think I have found the answer on this page: SilverStone Technology Co., Ltd.
The operating temperature, e.g. 10 ~ 50°C, refers to the temperature inside the computer case.
The internal temperature, e.g. 55°C, refers to the temperature inside the PSU.

That justifies the difference between 50°C and 55°C.

 

I just received the following reply from SilverStone, which confirms my above post.
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Thank you very much for using a SilverStone.
Sorry let you confusing, 50℃ is refers to your PC case temperature.
When reaches 55°C the fanless mode operation deactivates is refers to PSU’s internal temperature, this two are not same.
We don’t recommend the PSU long-term use in more than 50℃ environment, will cause the PSU’s internal temperature reaches 100°C or more,
Once long-term in high temperature environment, will reducing the output power of the power supply and also shorten the life of the power supply.
Thank you~

 

Bad choice of words on my part. I just meant you should not worry about it.

No, I don't agree. I think that is just some arbitrary number someone made up that, in no way, can be applied to all power supplies. Different supplies use different designs with different components. Different supplies start out with much different efficiency ratings. So there is no way all supplies would behave the exact same way. There will be some loss, for sure. But each supply would be different. And IMO, using a percentage instead of a fixed degree value would make more sense.

The case temperature vs PSU's internal temperature explanation makes sense. And if you read your SilverStone article, it talks about gains and losses in terms of percent, not some fixed number.

Assuming this is the computer listed in your system specs, check out the results of the eXtreme PSU calculator (the only calc worth its salt) here. Note I even padded the results by increasing CPU Utilization to 100%, adding 2 x 120mm case fans, and upping the Computer Utilization Time to 16 hours of use per day to build in some extra headroom.

The maximum load expected would be only 227W and they recommend 277W. So that 300W supply is plenty big - especially since it is a quality supply from a reputable maker.

 

Which one below is more reliable?

Intel Pentium G3240 - PSU Calculator - Build 6sXIws The result is 224 W
Power Supply Calculator - The most accurate PC wattage calculator The result is 132 W

Micro-ATX motherboard, Pentium G3240, 2 x 2GB DDR3, Seagate Barracuda SATA HDD 7200rpm, SATA DVD-RW drive, 2 x 8cm fan, 2 x 6cm fan, PS/2 mouse, USB keyboard, 8 hours per day.

 

I already said the eXtreme PSU calc is the only one worth anything. If you look at the other one, it hasn't been updated in over 3 years. It does not even know what DDR4 is. It does not list the G3240 so I don't know what you used there. It does not list 60mm fans either. So it seems pretty obvious which one is better.