Silent (fanless) PSU advice.

PSUs: The source of DC power for all components in the PC & often a big noise source.

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elsmandino
Posts: 28
Joined: Sun Sep 20, 2009 1:37 pm
Location: England

Silent (fanless) PSU advice.

Post by elsmandino » Fri May 04, 2018 2:00 am

Hello,

I am currently in the progress of trying to get my server as quiet as possible.

Here is my current setup:

MSI B85M-E45
G1840
12 GB RAM (2 x 4GB and 2 x 2GB)
2 x Samsung F4 2TB HDD
2 x WD Red 6TB HDD
64GB Crucial M4
Superflower Goldengreen HX 350W
Xigmatek Midgard Tower
140mm intake and 120mm exhaust fan (Antec F14 and F12 PWM, soon to be upgraded to F14 and F12 PWM PST)

The current weakest link seems to be the PSU - it definitely makes a bit of a "wooshing" sound that is definitely audible in the room in which it sits.

The server is on 24/7 and is used for scheduling/recording TV (via a SAT>IP box), serving data to other clients on the network.

I want to eventually add the ability to have some home automation on there but nothing strenouous like transcoding or anything like that.

Essentially, the CPU sits at idle most of the time and the harddrives are set to idle after 20 mins of activity (only of the WD Reds is regularly used, for recording purposes).

What PSU upgrade should I be looking at?

I deliberately chose the Superflower, because I knew the system was going to be constantly on and I wanted something with Gold or better rating. However, given that the machine is spending so much of its time doing nothing (i.e. at a low wattage), I needed something with the lowest possible wattage (on the basis that efficiency is going to be better at a higher utilisation of total power).

Any tips would be much appreciated.

Do you think I could get away with something like a Pico power supply?

Thanks

Derek Semeraro
Posts: 124
Joined: Sat Sep 23, 2017 6:49 am

Re: Silent (fanless) PSU advice.

Post by Derek Semeraro » Mon May 07, 2018 1:15 pm

i wouldnt recommend a fanless power supply. i'm sure there are power supplies out there that are very quiet and still cool effectively.

lodestar
Posts: 1683
Joined: Fri Aug 05, 2005 3:29 am
Location: UK

Re: Silent (fanless) PSU advice.

Post by lodestar » Mon May 07, 2018 2:58 pm

The cheapest Gold semi-passive PSU is probably the best solution. In practice, in the UK, if you want a fully modular PSU then there are a couple of potential choices both costing around £80. One is the Corsair 550 Watt Gold RM550X and the other is the Seasonic Focus Plus+ 550w Gold. The Focus+ is claimed by Seasonic to keep its fan off below about 30% load, I would expect the Corsair PSU to be similar. In your server scenario neither should run with its fan on at all, so there will be no fan noise.

elsmandino
Posts: 28
Joined: Sun Sep 20, 2009 1:37 pm
Location: England

Re: Silent (fanless) PSU advice.

Post by elsmandino » Tue May 08, 2018 4:49 am

Thank you both.
Derek Semeraro wrote:i wouldnt recommend a fanless power supply. i'm sure there are power supplies out there that are very quiet and still cool effectively.
Out of interest, what is it about completely fanless that means they should be avoided?

Lodestar, those two recommendations look perfect.

I have to admit, when I was on the lookout for a new PSU for the server, I was obsessed with getting something with the lowest wattage but with gold efficiency - the thinking being that the PSU would be more efficient whilst using a slightly higher % load.

The Superflower happened to be the cheapest gold-rated PSU, which probably explains the noisy fan.

Unfortunately, things did not work out as well as I had hoped - my system idles at around 25w.

That means that the PSU spends most of its time at just over 7% utilisation, so the gold rating is pretty much irrelevant at that load.

I was going to ask you whether going to 550w would make things that much more inefficient, but I suppose that that going from 7% to 4.5% is going to be an irrelevant issue.

Is being that inefficient at such a low wattage that important anyway? Perhaps efficiency could drop to the low 70s but we are talking about a lower efficiency on a small wattage (so the actual loss is quite minor).

Ultimately, I suppose my question now is whether 80+ ratings and wattages are really that relevant if you have something with a very small draw.

lodestar
Posts: 1683
Joined: Fri Aug 05, 2005 3:29 am
Location: UK

Re: Silent (fanless) PSU advice.

Post by lodestar » Tue May 08, 2018 5:49 am

elsmandino wrote:...my system idles at around 25w.
A test of the Seasonic Focus+ 550W by JonnyGuru puts the efficiency at 55w at around 83%. So I think you might see something more like 75 to 80% efficiency at 25w. However as it is only 25w this looks to me to be entirely acceptable. The only reason for suggesting 550w PSUs is because I can't find any hybrid (fan off at low loads) Gold PSUs below this capacity in the UK.

If you are willing to stray from Gold efficiency there is the Cooler Master MasterWatt Bronze PSU which is stated to keep its fan off up to 15% load. Again the smallest capacity is 550w but the price is much lower, it is currently on sale at Scan at £50. From this review by KitGuru it seems that its efficiency is not much less than the Seasonic, being measured as 80% at 55w. Note that this PSU is only semi-modular.

elsmandino
Posts: 28
Joined: Sun Sep 20, 2009 1:37 pm
Location: England

Re: Silent (fanless) PSU advice.

Post by elsmandino » Tue May 08, 2018 7:19 am

Thanks Lodestar - completely agree that at 25w, those sorts of efficiencies are more than acceptable.

I also agree that Gold is the way to go.

Your comments have given me a bit of an idea - before I buy anything, I might considering swapping the PSU from desktop PC.

It is an Antec 400w Hight Current Gamer - it has a 135mm fan that is much quieter than the Superflower.

I had never though of putting in my server, before, as it is only bronze rated - however, as per the below, this is going to be irrelevant.

You never know - it might just do the trick.

lodestar
Posts: 1683
Joined: Fri Aug 05, 2005 3:29 am
Location: UK

Re: Silent (fanless) PSU advice.

Post by lodestar » Tue May 08, 2018 8:40 am

This review of the Antec High Current Gamer 400w suggests around 70% efficiency at 25W, more than OK I would have thought.

elsmandino
Posts: 28
Joined: Sun Sep 20, 2009 1:37 pm
Location: England

Re: Silent (fanless) PSU advice.

Post by elsmandino » Wed May 09, 2018 4:32 am

Thank you Lodestar - you are an absolute star.

I did a few calculations (just for fun).

I have a current draw of 25w and, say 77% efficiency at that load, meaning my system needs 19.25w to run at idle.

If I swap the PSU for one that has 70% efficiency, the draw would only increase to 27.5w - negligible in the circumstances.

Thanks again.

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