Super high efficiency 300-400W PSU?

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Goof

New Member
Jan 27, 2021
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What exists for super high efficiency, lower wattage power supplies? Ideally in the 300-400W range, if not 275W. Both SFX and ATX form factors are fine.

I'm trying to avoid any rackmount-oriented PSU in particular unless they are provably silent (or silent at 2m) at 150W -- likely 100-120W -- or lower load. For example, total system idle may be as low as 40W. Cost not really a factor, but ideally it shouldn't be bananas (like 2x or 3x price) for TCO reasons.

For connectivity I need the usual ATX 20+4, CPU 4-pin, and four Molex connectors for a storage backplane. Modular heavily preferred, but not required.

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80 Plus Platinum power supplies are rare in lower wattages, and I've yet to find a Titanium one. Corsair has the SF450, but with 115V I may only hit 91.5% efficiency under my expected load (150W or less is expected peak), and only 87% efficiency at idle (probably 40-45W).

Seasonic has the Focus PX-550, but since the expected load is so low, efficiency is considerably worse compared to the Corsair SF450.

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I appreciate what you all can come up with!
 

BlueFox

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They're not common at low wattages like that because there's little demand and the higher efficiency makes a negligible difference. You're looking at a couple watts at idle and under 5W under load. In the scenario where your system runs 24/7, say half under load and half idle, I would estimate ~$3 annually in extra cost for 80+ Platinum vs 80+ Titanium. In most cases, the added cost would be greater than the energy savings over the lifetime of the power supply.

With that said, if you only need that little, why not just go for a 12V external power supply? They're lower wattage and you could forego any fans.
 

Goof

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Jan 27, 2021
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>"They're not common at low wattages like that because there's little demand and the higher efficiency makes a negligible difference."

Trust me, I've noticed this. :) 550-650W seems to be the real floor for Titanium now, and 450W seems to be the floor for Platinum with what's actually available. I'm aware I can go look at the 80Plus certification list, but for lower wattages you're looking at stuff that was certified closer to a decade ago and hasn't been available for eons.

My power consumption cost is a bit higher. Near Boston my yearly average is $0.266/kWh, and more like $0.286/kWh in winter. Yes, it's peanuts in the scheme of things ($2.33 per Watt per year), but there's other reasons I'm trying to drive the number down (mostly a challenge for myself). For someone in Germany though, things might matter even more (I think $0.55/kWh)! I'm curious how much a difference the future switch to ATX12VO will bring.

12V external certainly an option, but certainly looking for something more turnkey. Being able to just find the Corsair SF450 (best I've seen with measurements, including third-parties) so far, plunk down $85, and plug it in is hard to beat by comparison.

Believe it or not the project is a storage server that genuinely performs. Multi-volume, 72.5TiB usable (eight drives, plus dual NVMe for ingest/caching tier), capable of saturating 40GbE connectivity (yes!), with an anticipated idle (at 85% efficiency) of only around 40W, and peak load may be still sub-110W at the wall, and certainly sub-125W.
 
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Tom5051

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Jan 18, 2017
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Usually you can find the graph on the PSU manufacturer's website that will tell you how efficient the unit is depending on the load.
Find one that is most efficient around the power you expect to use.
 

Rand__

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Mar 6, 2014
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They're not common at low wattages like that because there's little demand and the higher efficiency makes a negligible difference. You're looking at a couple watts at idle and under 5W under load. In the scenario where your system runs 24/7, say half under load and half idle, I would estimate ~$3 annually in extra cost for 80+ Platinum vs 80+ Titanium. In most cases, the added cost would be greater than the energy savings over the lifetime of the power supply.
Half load is the most efficient are for a PSU though, more interesting are the edges... If you look at the 40-100W range then the differences are larger (->10% load). O/c its not so simple as its all relative to the specified max power and usually you get Titanium only at higher Wattages, but depending on the actual price difference it *can* make sense if you avoid the unregulated areas...

That said, for my low power 19" build I tend to use the Supermicro 340W 1U Multi-Output Power Supply (PWS-341P-1H) (if i can get it cheaply). Its not silent so does not fit the OPs requirements but it was the basically the lowest power platinum PSU i found (when i was looking a couple years back)


With that said, if you only need that little, why not just go for a 12V external power supply? They're lower wattage and you could forego any fans.
How do you connect these to a regular board? I have a board with 12V power in i think but wouldnt know how to convert the round plug that comes with these 12V PSUs to the 4 pin input on the board.

Another option are picoPSUs ... I played around with one a few years back too, but ultimately didnt deploy it since it was flaky on the intended box (prolly due to the Tapedrive drawing too much power after all).
 
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BlueFox

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How do you connect these to a regular board? I have a board with 12V power in i think but wouldnt know how to convert the round plug that comes with these 12V PSUs to the 4 pin input on the board.

Another option are picoPSUs ... I played around with one a few years back too, but ultimately didnt deploy it since it was flaky on the intended box (prolly due to the Tapedrive drawing too much power after all).
Like you said, simple adapter or the likes of a PicoPSU. Many newer Supermicro ITX motherboards don't even have ATX plugs anymore.
 

Bjorn Smith

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Sep 3, 2019
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I have my firewall running off a pico PSU - the only disadvantage to that is that you are stuck with an external power brick - which is silent but probably not very efficient :)
 

Goof

New Member
Jan 27, 2021
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Looks like this exists as of next month. No efficiency curves yet, but I'll be reaching out. Historically they've made adapter plates.


250W. Supposed 94% peak efficiency. Entirely passively cooled. My question is how high the efficiency will be at very low loads (50W or less).
 

Stephan

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Apr 21, 2017
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Bought three Seasonic Prime Titanium Fanless 600W ATX 2.4 (SSR-600TL) recently, won't get much more efficient at 40-50 watts. About 92% at 10% load. No sound at all. Super low ripple and stable voltage regulation. Long warranty. But expensive.