Question Silent low power PSU

pauliunas

Reputable
Jan 5, 2016
8
0
4,510
0
I want a silent PSU, preferrably with fanless mode. The system is very minimal: AMD Athlon 200ge, 2 RAM sticks, a bunch of hard drives but usually only one or two will be spun up at a time. No graphics card, I won't even connect a monitor to that thing. That should be under 50W, normally.

Ideally I want to run the whole thing fanless (35W TDP should be coolable without a fan, there are fanless coolers that allow as much - if not, I'll pop in a silent case fan with minimum RPM or underclock), so that means the PSU will be the noisiest part if it's not fanless.

Another notable thing is that I'm planning to keep that system running 24/7 so the PSU should hold up to that.

Price is, of course, still a factor so I'd like to keep it below $50 if possible... Given that my power consumption will be ridiculously low, the wear will be way less significant so I think even a "cheap" PSU should perform better than in an average gamer build. I might be wrong tho, because spinning hard drives up and down creates a rather high fluctuation and that might be bad (?), or maybe it doesn't matter because it's still way below 100W...
 

Karadjgne

Titan
Herald
Figure a minimum of 50w for the motherboard, that's going to include ram, USB, case fans, whatever. Also figure 20w per hdd as a broad coverage. Tack on the cpu TDP.

You could probably get away with using a pico psu, but I dislike those as they have 0 protective circuitry, no heat dissipation to speak of and no voltage regulatory circuitry, it's nothing much more than a pure power change to 12/5v and leaves you at the mercy of your own power source.
 

pauliunas

Reputable
Jan 5, 2016
8
0
4,510
0
Figure a minimum of 50w for the motherboard, that's going to include ram, USB, case fans, whatever. Also figure 20w per hdd as a broad coverage. Tack on the cpu TDP.

You could probably get away with using a pico psu, but I dislike those as they have 0 protective circuitry, no heat dissipation to speak of and no voltage regulatory circuitry, it's nothing much more than a pure power change to 12/5v and leaves you at the mercy of your own power source.
Well, 50W sounds a bit much for just a motherboard. For example:
https://www.guru3d.com/articles-pages/amd-athlon-200ge-review,5.html
This review says the whole system (including motherboard, CPU, RAM) consumes only 30W when idle, and only 50W when fully loaded.
I do not intend to keep it fully loaded, that will be quite a rare occasion actually. Most of the time it will be semi-idle, mostly just serving some files over SMB.
That being said, I do have way more hard drives than they did, but then again, only one or two of them are gonna be up at a time. 20W per HDD is also rather high, because of two reasons:
  1. Most of them will be off and not consuming any power
  2. Even if they all were on at the same time, the typical power consumption of a hard drive is below 10W, following an initial burst of up to 30W when it spins up. Source:
http://www.buildcomputers.net/power-consumption-of-pc-components.html

Lastly, I'm not worried about exceeding the power limit during boot or anything like that just because even if I add 30W for each hard drive with maximum future upgrades (as many hard drives as the case fits), the total power usage still doesn't exceed 400W, so any typical PSU will do. As for pico PSUs, I don't really care about those because they're too expensive for what they are and I'm not concerned about space savings anyway.

It's a bit expensive, don't you think?
And I thought about that one again... If it helps me save power, it might pay itself off after a year or two, or at least come close to, so I'm happy with that. I just want to make sure I'm getting maximum value for my money if possible :)
 

Flayed

Proper
Oct 8, 2019
231
35
140
5

Karadjgne

Titan
Herald
Exactly. I said budget for 20w per hdd, as that'll cover working loads, and spin up since it sounds like you'll be parking them when not in use. If using 3x hdds, chances are astronomically small of full 3x way spin up except at boot, so 60w will cover the possibility of 2x fully spin up at any given time, if they even use the full 30w.

Ram is around 3w per 8Gb, so I budget 10w to cover contingencies, differences in use and speeds, xmp etc. You only said 2x sticks, that could have been 32Gb, or @ 12w.

You don't want to plan a psu on actual usage, or that puts the psu at 100% loads. You'll want to plan the psu at 70%, so if actual usage maximums is 100w, the psu will want to be closer to 140w. So going overboard on guesstimates is healthier all around than planning down to the watt. Cover the possibility, not the probability. Murphy's law states the impossible will happen, sooner or later, and it always happens just when you don't want it to.

You could always get a cheap OEM tfx, sfx etc and swap/add a decent silent fan, or even pull the guts out of the case and run it open air with nothing but the case fan blowing on it.
 

pauliunas

Reputable
Jan 5, 2016
8
0
4,510
0
Exactly. I said budget for 20w per hdd, as that'll cover working loads, and spin up since it sounds like you'll be parking them when not in use. If using 3x hdds, chances are astronomically small of full 3x way spin up except at boot, so 60w will cover the possibility of 2x fully spin up at any given time, if they even use the full 30w.

Ram is around 3w per 8Gb, so I budget 10w to cover contingencies, differences in use and speeds, xmp etc. You only said 2x sticks, that could have been 32Gb, or @ 12w.

You don't want to plan a psu on actual usage, or that puts the psu at 100% loads. You'll want to plan the psu at 70%, so if actual usage maximums is 100w, the psu will want to be closer to 140w. So going overboard on guesstimates is healthier all around than planning down to the watt. Cover the possibility, not the probability. Murphy's law states the impossible will happen, sooner or later, and it always happens just when you don't want it to.

You could always get a cheap OEM tfx, sfx etc and swap/add a decent silent fan, or even pull the guts out of the case and run it open air with nothing but the case fan blowing on it.
To be more precise, 60W covers 2 drives spinning up at the same time, or 6 drives already fully spun up.

And don't worry, you don't have to tell me about headroom. What I was trying to say is that I'm already in the range of 10-20% of full power, and even the theoretical maximum power draw with all possible upgrades is still below 400W, closer to 300W. Hence, when I talk about power consumption, I'm not a tiny bit concerned about a PSU's capacity because the smallest you can get is already obviously too powerful. What I'm concerned about is the noise, and what matters for that is average short term power consumption. Bursts such as hard drives spinning up don't matter at all here because they're not long or frequent enough to affect the fan speed noticeably.
 

pauliunas

Reputable
Jan 5, 2016
8
0
4,510
0
Quality PSUs are expensive. You pay for the peace of mind that it will last and not go up in smoke damaging other components.

This is a more budget-friendly option:
PCPartPicker Part List

Power Supply: Corsair CX (2017) 450 W 80+ Bronze Certified ATX Power Supply ($53.88 @ OutletPC)
Total: $53.88
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2019-10-21 10:15 EDT-0400
What about this one?
https://www.bequiet.com/en/powersupply/1280
 

Karadjgne

Titan
Herald
Is there a physical size limitation? You could easily run a cheap psu with that load out, just stick a 140mm fan in top, which will keep rpm down, and consequently noise, as it'll move enough air to esatisfy the thermistor circuit. Or even easier will be a semi-passive unit (true fanless are seriously expensive due to design and circuitry) which don't even spin up the fan until the psu reaches a certain temp. Push come to shove you could add a thermistor to the fan output and create a passive mode on any psu.
 

pauliunas

Reputable
Jan 5, 2016
8
0
4,510
0
Is there a physical size limitation? You could easily run a cheap psu with that load out, just stick a 140mm fan in top, which will keep rpm down, and consequently noise, as it'll move enough air to esatisfy the thermistor circuit. Or even easier will be a semi-passive unit (true fanless are seriously expensive due to design and circuitry) which don't even spin up the fan until the psu reaches a certain temp. Push come to shove you could add a thermistor to the fan output and create a passive mode on any psu.
No, there's no real size constraint. Quite the contrary, I have an mATX case that will fit a standard ATX PSU very nicely, whereas with more compact form factor PSU I would have to think where and how to put it in the case. So a cheap PSU would probably work, but they often don't have fan speed control. Or if they do, sometimes the absolute minimum RPM is still quite loud.

My goal is to find a semi-passive PSU as you said, but it's very hard to find one because most websites don't have a filter for that. I've heard they exist, but that's about it. I don't know how expensive they are or how to find them.

Another idea that recently popped up in my head is that a more efficient PSU might pay itself off, and as a bonus it might have longer warranty (I've noticed that usually efficiency and reliability come together). But I don't know if I can expect a big enough increase in efficiency for it to pay back during 3-5 years. After building this thing, I estimate my power bill to grow by about 50-60 per year, so that would mean a $40 more expensive PSU should bring almost 20% better efficiency in order to pay back in that period.
 

Flayed

Proper
Oct 8, 2019
231
35
140
5
Another idea that recently popped up in my head is that a more efficient PSU might pay itself off, and as a bonus it might have longer warranty (I've noticed that usually efficiency and reliability come together). But I don't know if I can expect a big enough increase in efficiency for it to pay back during 3-5 years. After building this thing, I estimate my power bill to grow by about 50-60 per year, so that would mean a $40 more expensive PSU should bring almost 20% better efficiency in order to pay back in that period.
You won't make the money back from savings on your electricity bill. You will save money by not having to replace it as quickly as a budget unit.
 

pauliunas

Reputable
Jan 5, 2016
8
0
4,510
0
I checked this list:
https://docs.google.com/spreadsheets/d/1i6gYAlEEB8Wpbr4E3jY3ctuYvNR5SiuokzPLb5WiQlw/edit#gid=0
The Be Quiet System Power 9 is rated as a tier 4 unit with a 3 year warranty. I would not recommend it.
Interesting list, thanks. I usually don't pay too much attention to such lists because with relatively low desktop uptime, I'm willing to accept the small risk of it failing. But for this one, I guess I have to suck it up because the uptime will be several times higher.

I'm trying to read some reviews for the two PSUs you gave before and it seems like the Corsair one doesn't have a fanless mode. Is that right? In that case I'd rather spend those $20 extra to get one that includes fanless mode.

You won't make the money back from savings on your electricity bill. You will save money by not having to replace it as quickly as a budget unit.
yeah that makes sense... But then again, for some reason I don't expect any PSU to last more than 5 years.
 
I checked this list:
https://docs.google.com/spreadsheets/d/1i6gYAlEEB8Wpbr4E3jY3ctuYvNR5SiuokzPLb5WiQlw/edit#gid=0
The Be Quiet System Power 9 is rated as a tier 4 unit with a 3 year warranty. I would not recommend it.
That's actually a pretty darn good list. I usually roll my eyes when I see tier lists mentioned. It still has a few unavoidable flaws that come with such lists, but that is about as good as you could ever hope for.

The Be Quiet System Power 9 is a budget PSU. You don't want something like that for a 24/7 system.
 

pauliunas

Reputable
Jan 5, 2016
8
0
4,510
0
The Seasonic Focus 450w mentioned earlier looks like the perfect PSU for this application.
That's actually a pretty darn good list. I usually roll my eyes when I see tier lists mentioned. It still has a few unavoidable flaws that come with such lists, but that is about as good as you could ever hope for.

The Be Quiet System Power 9 is a budget PSU. You don't want something like that for a 24/7 system.
Thanks guys! I found a Seasonic Focus Plus 450W Gold for 74EUR over here, so I'll grab it
 

ASK THE COMMUNITY

TRENDING THREADS