How much is a % of psu efficiency worth in £(and noise)

ginjaninja

ginjaninja

ginjaninja

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Joined
30 Jul 2007
Posts
1,281
PC Type - Media server / HTPC / Gaming
Spec
Overclocked Haswell i7 4-4.5 ghz. 4 Ram sticks. 10x3tb Green HDDs, 1x SSD,GTX780. COSMOS II, 5 Fans, PSU?
HDDs are sata motherboard attached individually so can power down when not in use.

Usage - on 24/7, watching media 1hr per day, Playing Games 1hr per day. (possibly 24/7 metric is the only significant one to keep simple)

Anticipated Lifetime - 10yrs

Priorities Highest 1st
Not spending money for no tangible benefit
Lifetime cost over cost of initial purchase
Quiet

Avg anticipated Cost per KWH over next 10 yrs=25p
Idle load=please suggest (GPU idle i understand is in order of 80W)


http://extreme.outervision.com/PSUEngine

suggests a 500W PSU but i understand a larger psu may be quieter under load but less efficient at idle. Maybe i need to look at psus that are very efficient at low loads (maybe all? or none? are any better or worse)

Has any one ever investigated/Can anyone suggest an appropriate power supply / suggest a calculation or result for annual value in a %of efficiency for the psu.

thank you
 
With that rig, you need a good efficiency rating, This means the machine will always be stable and it'll never be drawing more than it needs to.

Also it'd be helpful to have a PSU with 'adaptive fan control', which means it is fanless when under very little strain, then the fan only ramps up when more power is drawn.

I would recommend this piece of kit:

YOUR BASKET
1 x Seasonic 660w '80 Plus Platinum' Modular Power Supply £129.95
Total : £140.45 (includes shipping : £8.75).

 
Doomedspeed said:
With that rig, you need a good efficiency rating, This means the machine will always be stable and it'll never be drawing more than it needs to.

Also it'd be helpful to have a PSU with 'adaptive fan control', which means it is fanless when under very little strain, then the fan only ramps up when more power is drawn.

I would recommend this piece of kit:

YOUR BASKET
1 x seasonic 660w '80 plus platinum' modular power supply £129.95
total : £140.45 (includes shipping : £8.75).

Click to expand...

thank you for your suggestion.
i can see how adaptive fan is relevant, i also know some parts dont turn on the fan at all at lower loads (but that might mean an overspecced wattage which i understand is the biggest enemy of value, so adaptive fan gets a +)

i also made a calculation/further assumptions for comment.
adding evidence as mentioned above efficiency might well be worth paying for when viewed over the longer term for an always on device

idle kw usage 0.125
hours in year 8760
annual kwh 1095
annual cost £274
80 gold over bronze @ 20% loading 7%
80 platinum over bronze @ 20% loading 9%
80 titanium over bronze @ 20% loading 13%
gold platinum titanium
annualsaving over bronze £19.16 £24.64 £35.59
over 10 years £191.63 £246.38 £355.88

strangley the psus in this review dont meet the standard listed on wiki for 20% load.
http://www.tomshardware.com/reviews/80-plus-platinum-power-supply-efficiency,3327-13.html
http://en.wikipedia.org/wiki/80_Plus#Efficiency_level_certifications
 
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Your calculations look good.

I would just say that to deliver the same power, a 90% efficient PSU will use 11.1% less power at the wall than an 80% one (calculation below).

80%: for every watt delivered the PSU takes 1.25 W from the wall.
90%: for every watt delivered the PSU takes 1.11 W from the wall.
Ratio of these is 0.889, so the 90% one is better by 11.1%.

With a load of 0.125 KW you're talking about the 80% one pulling 0.156 KW and the 90% one pulling 0.139 KW, which is a difference of 152 KWh per year (about £20 at 13p/KWh). Over 10 years, £200. Quite a significant difference!

ginjaninja said:
Strangley the psus in this review dont meet the standard listed on wiki for 20% load.
http://www.tomshardware.com/reviews/80-plus-platinum-power-supply-efficiency,3327-13.html
http://en.wikipedia.org/wiki/80_Plus#Efficiency_level_certifications
Click to expand...

It looks like they do to me. Platinum at 20% load need to be 90% efficient, which all those tested achieve?
 
OCers are not alone, no one sells titanium rated psus in uk, particularly relevant for always on users with larger psus given the mandated efficency at 10% load (the other standards dont specify at 10%)
 
PicoPSUs at low load are a tad more efficient than most 80% PSUs for HTPC use iirc. You obviously have lots less wiggle room on wattage though
 
A pico PSU would be no use, as the 780 can pull 250 watts by itself.

I think one of the difficulties with this is that PSU efficiency generally drops off quite sharply below 25% load?

Your rig will be spending a large majority of it's time, idle.

I've recently gone through a similar process of economising, only I built a second PC from old components to run as a low wattage media server. Picked up a mATX board with integrated graphics from the members market a while back and I've actually just bought a Seasonic 360w Gold from there today, to replace the ancient 300 watt OEM unit that's powering it at the moment. Need to dig out my plug-in energy monitor to make some comparisons.

But this means that I can put my gaming rig to sleep for 23 hours a day.
 
Love that PSU that Doomdspeed suggests.

I mention it a lot it seems but it comes with 7 years warranty, which is a good chunk of your 10 years.

If the fan is not spinning for a lot of its life then that is a further saving of 2.4 watts an hour going on a guesstimate of 2.5 watts an hour :p adds up over 10 years .
 
d_brennen said:
As I said, for HTPC use and like you said, using high wattage parts for playing back media is something of a waste :)
Click to expand...

Sorry yes I see what you were saying.

And yes the Pico PSU are great for low loads like that, and the fact you can have a smaller case and are usually fan-less, so completely silent :)
 
ThaReaperGuy said:
I may be missing something as I've just awoken but, is there much point of having it run 24/7 for you to use it for only 2 hours a day?
Click to expand...

Its a media server, accessed by xbox, tv, tablets around the house, The house is 3 stories and i would hate to have to go up 2 flights (to switch on) just to watch media on tv downstairs. But maybe i should spend the money on a remote switchon function...anyone aware of the such a product, it would need to be accessible remotely over internet as i watch media when on the road as well.

I take the point about a 2nd rig, the 80W idle from the gpu blows away the benefit of improved efficiency psu when compared to a dedicated media server drawing significantly less at idle (assumed). Maybe i should be concentrating in this area if i had all the parts anyways.

What i really need is a gaming gpu which doesnt draw power in idle (assuming this is the lions share of the idle draw)..then i could stick with the one rig (which is what i really want)
 
Most motherboards support WOL (Wake-On-Lan). I use an app on my phone to fire a magic packet which wakes the Server from sleep. Unfortunately I've not found an app that works that can put it back to sleep and with my router I can't use WOL over WAN, only LAN.

Edit: With regard to a low idle GPU I'm not sure if such a thing exists. I built a system for a friend a while back and the motherboard has Lucid Logix Virtu MVP in built which means you just connected the display to the integrated graphics port and the software automatically handles whether it uses the integrated graphics for OS and 2D work or the discrete card for 3D gaming.

I'm not sure how much of a power saving it offers because it would depend on whether the motherboard could completely shut down the discrete card when not in use.

http://www.lucidlogix.com/
 
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oceaness said:
I'm not sure how much of a power saving it offers because it would depend on whether the motherboard could completely shut down the discrete card when not in use.

http://www.lucidlogix.com/
Click to expand...

interesting power\cost savings if it could, it would be ideal for this 24/7 application with the odd bit of gaming in a single rig; i cant find anything on the internet to verify it does. im not even sure if its a software or hardware solution.
 
ginjaninja said:
I take the point about a 2nd rig, the 80W idle from the gpu blows away the benefit of improved efficiency psu when compared to a dedicated media server drawing significantly less at idle (assumed). Maybe i should be concentrating in this area if i had all the parts anyways.
Click to expand...

I would be quite tempted to suggest a Synology/QNAP NAS or HP miniserver in that context - my NAS uses <10 watt when idle and <40 watt under heavy use with all the discs spun up - they are pretty decent for serving media, etc. off tho the extra cost of buying one might offset any difference in power consumption.
 
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