Power Supply A Guide to 12V PSU

[SilverJS]

So I'm kind of finalizing my parts list for Meanwell-only dual-PSU S4M, and just want to make sure, before I splurge - if I always leave my computer on, do I need that load switch from Aquelito? To me, as long as the computer can properly power manage and go to sleep as required, I'm happy. The only time I'd shut down is if the house is really overflowing with guests and we'd have people sleeping in the same room I keep the computer in (in which case, the flashing power button might be a distraction to someone trying to get to sleep). In those cases, I could either unplug the power button LED, or more likely, just shut down the computer and unplug it from power. It's just that, as cool as that switch is, it's a fair bit of wires and extra volume, and I'm not yet convinced I need it...

Thoughts?

 

[Thehack]

So I'm kind of finalizing my parts list for Meanwell-only dual-PSU S4M, and just want to make sure, before I splurge - if I always leave my computer on, do I need that load switch from Aquelito? To me, as long as the computer can properly power manage and go to sleep as required, I'm happy. The only time I'd shut down is if the house is really overflowing with guests and we'd have people sleeping in the same room I keep the computer in (in which case, the flashing power button might be a distraction to someone trying to get to sleep). In those cases, I could either unplug the power button LED, or more likely, just shut down the computer and unplug it from power. It's just that, as cool as that switch is, it's a fair bit of wires and extra volume, and I'm not yet convinced I need it...

Thoughts?

The issue is not sleep necessarily. Sometimes the LEDs and the fans stay on. Sometimes the fan run at 100%.

I solved it by just keeping the computer idle. I'd check the power consumption of your setup, and see where it stands on idle electricity cost. If your electricity bill averages 0.20 USD, and you average actual time off vs idle/power on at 18 hrs a day, your idle cost would be approximately $7.5 per month, assuming approximately 70W idle.

 

[SilverJS]

The issue is not sleep necessarily, is that sometimes the LEDs and the fans stay on. Sometimes the fan run at 100%.

But the situation you describe above is when the computer is shut down, correct? Would that situation present itself during normal usage, or during normal sleep?

 

[Thehack]

But the situation you describe above is when the computer is shut down, correct? Would that situation present itself during normal usage, or during normal sleep?

during off and sleep from my experience. only keeping it on idle solves it. I also added some math to the previous post.

 

[SilverJS]

Ah, OK. So, to restate what you said, with a view to confirming I understand correctly :

One way to forego using Aquelito's switch, from your research and experience, is to simply not let the computer sleep but limit it to idle.

That correct? Also, does letting the display sleep (but not the CPU - display only) change any of what you said?

Your usage math checks out (and is even optimistic - I am quite unlikely to use the computer six hours a day!), but ultimately, I'm not that concerned about power consumption, or the costs of such.

 

[Thehack]

Ah, OK. So, to restate what you said, with a view to confirming I understand correctly :

One way to forego using Aquelito's switch, from your research and experience, is to simply not let the computer sleep but limit it to idle.

That correct? Also, does letting the display sleep (but not the CPU - display only) change any of what you said?

Your usage math checks out (and is even optimistic - I am quite unlikely to use the computer six hours a day!), but ultimately, I'm not that concerned about power consumption, or the costs of such.

The display on/idle/off does not change any of this.

 

[SilverJS]

OK, thank you for your contribution. I guess I have a decision ahead of me!

 

[alexs]

Anyone tried measuring idle power consumption for Meanwells?

I finally switched to a 12V setup with PicoPSU and Meanwell PPS-200-12, and was surprised to find out the PSU draws about 7W with no load. At this point, it's not even about power saving so much as it is about thermals. When the system is "off" or sleeping, the fans are not spinning, but the PSU is still producing almost as much heat as it would at max CPU load (assuming ~100W load and ~90% efficiency). That heat has to go somewhere.

Are newer units like EPP better in this respect?
Are there any other ideas? (other than leaving it as is)

I'm aware more powerful units have PS-ON and 5VSB but actually using those requires a custom PDCB and/or a control board.

 

[Thehack]

Anyone tried measuring idle power consumption for Meanwells?

I finally switched to a 12V setup with PicoPSU and Meanwell PPS-200-12, and was surprised to find out the PSU draws about 7W with no load. At this point, it's not even about power saving so much as it is about thermals. When the system is "off" or sleeping, the fans are not spinning, but the PSU is still producing almost as much heat as it would at max CPU load (assuming ~100W load and ~90% efficiency). That heat has to go somewhere.

Are newer units like EPP better in this respect?
Are there any other ideas? (other than leaving it as is)

I'm aware more powerful units have PS-ON and 5VSB but actually using those requires a custom PDCB and/or a control board.

7 watts is fine.

Did you also disable any standby power features? Like USB charging?

Is this also actual no load? DC-DC fully disconnected?

 

[alexs]

No load whatsoever, output connectors were not plugged into the PSU.

In sleep mode (CPU power connected, PDCB connected, system sleeping, fans & pump stopped) I'm reading about 8W.

 

[m0t0k0]

I have been looking at using a mean well 400-12 power supply in an upcoming build.

I was disappointed when researching to find the PSU will not be controlled by the MOBO and powered down when not in use.
I know a load switch can be used to allow power to the GPU to be ceased but doing some research it seems the facility is built into the PSU already.

From what I understand the ATX specification will allow a PSU to "soft start" by driving the PS_ON pin low. Conversely driving it low or leaving it open (note: it is pulled high internally in the ATX power supply itself) should cause the PSU to switch off.

The EPP-400-12 PSU has a PS_ON pin so we should be able to use this to control the PSU.

From what I understand TheHack tried this but was unable to get it to work and thus designed the load switch.

I was reading through the EPP-400-12 spec sheet and found this
Power on: PS-ON = "Hi" or " > 2 ~ 5V" ; Power off: PS-ON = "Low" or " < 0 ~ 0.5V"

This is the reverse of the ATX spec. Is this why it would not work?

Can we not pull this pin to GND when we want to shut down the PSU?
Maybe had a load sensor on the +12V line then causes a relay to close when the load drops below an idle state shorting the PS_ON pin to GND?

 

[NateDawg72]

In short, yes, the PS-ON being the reverse of ATX is why we haven't had sync so far and why load switches have been used.

That's about all I can say, I would love if we can make sync happen. I don't have the know how to figure it out myself but if you or someone else can come up with a solution I'd be happy to try it on my RPS-400-12

 

[m0t0k0]

In short, yes, the PS-ON being the reverse of ATX is why we haven't had sync so far and why load switches have been used.

That's about all I can say, I would love if we can make sync happen. I don't have the know how to figure it out myself but if you or someone else can come up with a solution I'd be happy to try it on my RPS-400-12

Hi sorry I was not aware it was known that that was the issue. There are 19 pages in this thread and I did not read all of them.

I'm new to SFF and 12V PSUs so I'm don't think I'll be much help

 

[NateDawg72]

I am still fairly new to PSUs as well, and I don't have previous electrical knowledge I can crimp wires, follow guides, look up pin-outs but when a creative solution is needed like for sync issues I am not much help

 

[Thehack]

The issue is not really that, as those problems are quite straightforward to solve. The main issue from a product design standpoint is that meanwell is the only one with this function.

This means I were to design something that works with this function, it requires another layer of complexity to also support psu that only outputs 12V and has no other function.

So this requires a bit more than modifying off the shelf parts, and is thus a bigger oem project. I'd like to go back and solve this problem if my J-hack shop takes off. At the moment it is just simpler to use a solid state relay circuit (load switch).

 

[Maliniorz]

Hello, it's my first post here.

I'm assembling mini ITX PC with AMD APU (case is 217 x 80 x 235 milimeters in size btw) and I found Meanwell EPP-200-12 PSU very interesting for my build. Everything fits pretty well in this case.

But my problem starts when it comes to wiring on the AC 230V side: power sockets in my country (Poland) have different L and N layout and there are no standards, like in USA, to do L on the right side and N on the left side.

Do I need to be very cautious while connecting power cord to wall socket? In Meanwell docs I've read that EPP-200-12 use separate inputs for L and N. To clarify I'm sending you an example from my home.

I travel a lot and I found this very problematic because this means that I need to carry additional cable and voltage tester screwdriver to find out where the hotline is.

 

[Thehack]

As far as I know, polarity is not an issue.

 

[picov]

Hi,
I'm looking for an external 12V high quality power adapters (power bricks) into the range of 160-400W but it seems that the market not offer so much.

Does the suggested Meanwell PSU (post#1) exists also as external power brick version?
Does the G-Unique modded DELL units are the only viable option ?
Any valid product to try?

Thank you.

 

[Thehack]

Hi,
I'm looking for an external 12V high quality power adapters (power bricks) into the range of 160-400W but it seems that the market not offer so much.

Does the suggested Meanwell PSU (post#1) exists also as external power brick version?
Does the G-Unique modded DELL units are the only viable option ?
Any valid product to try?

Thank you.

You can buy a GST280A12-C6P. I believe it is a 400W unit derated for 250W convection. So it is a much more capable unit than it seems. However it only comes with a 6 pin connector which limits how much power you can safely use.

 

[alexs]

Follow-up to my post above. Replacing MW PPS-200-12 with MW EPP-200-12 solved pretty much all issues.

PPS-200-12 no load 7W sleep 8W system idle 28W
EPP-200-12 no load 0.3W sleep 2.2W system idle 24W

EPP is also completely silent at system idle and above. There's barely audible whine with no load, which however becomes louder when the system is sleeping. PPS did make some noises at pretty much any power level. Still, EPP's control circuitry seems to be struggling with loads around 1%.

EPP is also much cooler despite being smaller overall and having smaller radiators. I'm picking about 40C at idle, and about 30C at sleep. For comparison, PPS stayed around 50C at idle and heated up above 60C at sleep. Higher loads turned out to be completely irrelevant for PSU temps, additional cooling from the fans spinning up completely negates increased heat output.

Notably, EPP flat-out outperforms BQ TFX (an 80PLUS Gold rated dedicated PC PSU) in all modes except sleep. It's cooler, quieter and draws less power off the wall. But a secondary 5VSB supply still seems to be a necessity for good sleep mode performance.

Avoid PPS series I guess. Just not a good fit for this particular application.