Is 55℃ acceptable to a PSU?

[Matthew Wai]

I recently bought SilverStone ST30SF (V1.0) , whose product page says its fan will not start spinning unless its internal temperature has reached 55℃. Do you consider 55℃ acceptable to a PSU?

 

[blockgameraran]

Yes, it’s perfectly fine. The fans don’t spin. Because it is not needed. 55 deegres is not much

 

[Matthew Wai]

Not much what? Not much of a problem?

 

[4745454b]

55C isn't bad for a CPU or GPU, but that's much to hot for a PSU. Those are normally rated for 50C max, not 55C. I'd be very surprised the fan was set to turn on at 55C. Here is JG review of that unit.

http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story4&reid=368

Tests one and two the fan was off. Note that it's not just temp that decide the fan speed, but load as well. You can tell because test 3 has lower temps than test 2, but the fan was off on test two because it wasn't outputting 50% of its capability. 50% of output with 32C temps means the fan turns on, while 40% of it's output at 33C means the fan is off.

I'm not sure where you see 55C means the fan turns off. (Unless I'm looking at the wrong PSU.) I would not at a PSU hit 55C. That's too hot for a PSU.

 

[Matthew Wai]

I'm not sure where you see 55C means the fan turns off.

https://www.silverstonetek.com/product.php?pid=458&area=en

"3.Ultra-quiet 80mm fan with intelligent RPM control guarantees cool performance and silent operation with minimum of 18dBA during fan operation. The fanless mode operation deactivates when PSU’s internal temperature reaches 55°C. (V1.0)"

 

[Matthew Wai]

I found the following statement at http://www.tomshardware.com/forum/id-3429508/psu-advice-wanted-eco-mode.html#19760763

1. Increasing PSU fan longevity since PSU fan doesn't run until PSU internal temp reaches 55°C.

 

[4745454b]

That's a different PSU. The eco mode setting will change depending on the quality of the PSU. JG tested and found the fan turns on around 30C for this model. I'm not sure why that other PSU allows 55C. That's really hot for a PSU.

 

[Matthew Wai]

That's a different PSU.

I knew it was a different PSU. The point is that 55°C seems acceptable to some other PSUs, not just mine.

 

[Matthew Wai]

I'm not sure why that other PSU allows 55C.

The following PSU allows even 85°: https://www.quietpc.com/qt-07400f

 

[4745454b]

85C would be a horrible idea as the main cap is rated for either 85 or 105C. To run the main cap that close the edge is just a bad idea. 55C with an 85C main cap isn't bad. But if the PSU is rated for 100% output at 50C, and you run it at 55C, that's running it out of spec. Typically you'll see lower output with more temps. So if it's rated for 100% at 50C, you might see it also rated at 90% at 55C, or 90% at 65C. It's hard to find this info however. And every platform will be different. 50C is my hard upper limit simply because that's the common rated temp.

The original green label CX platform was rated for 30C. 55C would probably kill it.

 

[Matthew Wai]

I think the manufacturers must have some reasons to justify the temperature settings unless they want the PSUs to die of heat.