Fans stay on after shutdown (Node 304/AsRock)

[serendipity]

I'm in the middle of building my first NAS:

• Fractal Design Node 304 case
• ASRock Rack MT-C224 motherboard
• Seasonic G-360 (aka SSR-360GP) power supply unit

If I plug the chassis fans into the chassis' fan controller, and power that fan control controller directly from the PSU, then the fans stay on indefinitely after shutdown. This seems wrong. I was expecting that the fans would power off after shutdown. Note that the CPU and its fan correctly turns off at shutdown.

Is this a motherboard problem? A PSU problem?

The workaround is of course to plug the chassis fans into the motherboard. This might be a better option anyway. Still, I'm unnerved by the idea that my machine doesn't power off properly.

 

[Ericloewe]

power that fan control controller directly from the PSU

That's an odd thing. I assume the hard drives are also permanently powered, right?

 

[serendipity]

I assume the hard drives are also permanently powered, right?

Good question. I hadn't yet put the drives in.

The hard drives are still problematic: if plugged into the PSU, then when the computer is plugged in, but before it is turned on, the hard drives will start. However, the hard drives are better in that they do turn off when the computer is shutdown.

Thanks for confirming my suspicions something is weird. I'll contact the motherboard manufacturer. However, there's little point worrying about it, because it behaves properly if I instead power the drives from the motherboard.

 

[Ericloewe]

I'd replace either the motherboard or the PSU and see which one is causing the problem.

 

[rogerh]

If you check the voltage on the pin on the 24 pin PSU plug which enables the power supply you will be able to tell which is defective. The pinout is freely available on the Internet. The fact that the fans behave differently from the disks hints that the either the 12V is low or the 5v is off after shutdown, but the PSU is not completely off. Nothing the motherboard can do can cause this (power is either enabled or not) so, to me, this strongly points to the PSU being at fault. But if the above power enable pin is low when the fans are spinning this is definitely a power supply fault. At least, I don't think any ATX power supply should turn on anything except 5V standby when not enabled.

 

[serendipity]

If you check the voltage on the pin on the 24 pin PSU plug which enables the power supply you will be able to tell which is defective. [...]

Thanks for the detailed reply. I hadn't spotted it.

In the end I was able to borrow a different PSU. That empirically ruled out the PSU being at fault. However, I can't explain why that contradicts your guess.

I now realise the AsRock Rack MT-C224 motherboard doesn't take a 24 pin PSU. It takes a proprietary 18 pin supply. The board came with a 24 to 18 pin adapter (which curiously transfers fewer than even 18 wires). My best guess is the board shutdown is broken by design due to this.

So, I'm returning the motherboard for another model. Problem solved.

 

[rogerh]

Thanks for the detailed reply. I hadn't spotted it.

In the end I was able to borrow a different PSU. That empirically ruled out the PSU being at fault. However, I can't explain why that contradicts your guess.

I now realise the AsRock Rack MT-C224 motherboard doesn't take a 24 pin PSU. It takes a proprietary 18 pin supply. The board came with a 24 to 18 pin adapter (which curiously transfers fewer than even 18 wires). My best guess is the board shutdown is broken by design due to this.

So, I'm returning the motherboard for another model. Problem solved.

That's very interesting. I think I will look up the MB manual if it is freely available. There is actually no obvious reason to turn of the PSU when the OS shuts down on a server motherboard, as the only routinely used conditions are working and disconnected, rather than shutdown with power connected. But I didn't know there were standard boards set up like this. I expect it is usual for embedded boards. The only question it leaves is whether the bios can be set to boot the OS when the board is power cycled.


Edit: As you say, the only connection to the board seems to be +12V and ground. And the adapter cable must permanently turn on the ATX PSU when the cable is connected. I think I would be perfectly happy with that for a server, once I understood what was happening: and provided it can be set to reboot when power cycled.

 

[Ericloewe]

Thanks for the detailed reply. I hadn't spotted it.

In the end I was able to borrow a different PSU. That empirically ruled out the PSU being at fault. However, I can't explain why that contradicts your guess.

I now realise the AsRock Rack MT-C224 motherboard doesn't take a 24 pin PSU. It takes a proprietary 18 pin supply. The board came with a 24 to 18 pin adapter (which curiously transfers fewer than even 18 wires). My best guess is the board shutdown is broken by design due to this.

So, I'm returning the motherboard for another model. Problem solved.

That explains things. The adapter probably just shorts the PWR_ON pin to GND.

I imagine Supermicro's Avoton boards act similarly when powered by their 12V inputs, but they do take a 24-pin connector, alternatively.

 

[rogerh]

Several things to think about if one wants to use the the board in any kind of 'shutdown' mode with mains power connected to a standard PSU. To what extent does the motherboard shut its own circuitry down when the OS shuts down? Does it switch power to cards or the SATA power out connector? Or do the drives just go into some form of standby set by the SATA signal cable? How many drives can you connect to the SATA power out on the MB, and is it ever limited by the (presumed MB supplied) 5V rather than the 12v supply?

Probably not a problem if the plan is to have the server always on except during maintenance or AC power loss, but not things we normally have to think about with standard PC MBs.

 

[JoanTheSpark]

The AsRock MT-C224 hast got a ATX 8 pin (12V only) connector on the backpanel (probably for server purposes) and on the board there is a mini-ATX style connector (called PDB power connector) that only takes the 12V and the green wire (PS_ON), nothing else. This connector is connected to the PSU via an adapter that also grabs the 12V of the intel 4-pin ATX connector.


This motherboard can't shutdown a standard PSU as otherwise the MB won't be reachable via BMC/IPMI due to the fact that it is only powered by 12V from the PSU.
This motherboard doesn't take the +5VSB at all, the PSU has to stay on all the time.

I have got the fans in the motherboard, as otherwise you need more connections (90% of failures in electronics are connections) to get the RPM/PWM signal to the fans..
The board provides 4 case fan sockets, so unless you got more than that there is no need to plug them directly into the PSU?!

My current PSU is a fractal design run-of-the-mill SFX 300W (FSP300-60GHS) and works so far.
The only thing that's not working properly is switching the NAS on via BMC/IPMI after a cold start (PSU switched OFF, then ON).. but can't rule out network config issues as I'm new to this and have it running since Sunday only.

...
How many drives can you connect to the SATA power out on the MB, and is it ever limited by the (presumed MB supplied) 5V rather than the 12v supply?
...

There is an extra 4-pin ATX socket on the board (plus 6 position SATA power cable) to power the SATA drives from the boards 12V supply, so if you plug the drives into that and not directly into the PSU they will be shut down properly if they're not supposed to be ON.

 

[serendipity]

The only question it leaves is whether the bios can be set to boot the OS when the board is power cycled.

Yup, it can. When the mains is reconnected you can have it do whatever you want. It can turn on, stay off, or restore the previous on/off state.

That explains things. The adapter probably just shorts the PWR_ON pin to GND.

I imagine Supermicro's Avoton boards act similarly when powered by their 12V inputs, but they do take a 24-pin connector, alternatively.

This motherboard can't shutdown a standard PSU as otherwise the MB won't be reachable via BMC/IPMI due to the fact that it is only powered by 12V from the PSU.
This motherboard doesn't take the +5VSB at all, the PSU has to stay on all the time.

Ah, thanks for the explanations everybody. I now understand how this behaviour is perfectly acceptable in a cloud (sorry for using the term) server. My usage, however, will only be for part of the day.

The standby/off power draw of the board is 10W, according to a meter of unknown accuracy which I have. That's about £10/$20 a year. In fairness that's not much compared to the cost of the building the NAS (or the running costs when the whole NAS is powered on), but it's enough to make me uncomfortable.

JoanTheSpark, enjoy your highly specced motherboard.