How to choose PSU compatible to your system?

[Tomas Liumparas]

Hello folks,

I believe the topic speaks for itself.
What to look at?
As far as I know from reading in here, GOLD CLASS 80 is recommended. How about the power of the supply? 50% more than total amount of components' requried power?

Is 50% too much? I read something about the spin up of the drives, I jsut thought it would be nice to gather everything in this thread :)

 

[jgreco]

The usual way would be to determine the power your components require. Separately calculate the 12V spinup current required for the drives; do NOT assume that just because you have a 300W power supply and the total V*A < W you're okay. Most drives take 12V at about 2A to spin up, and you really do need a power supply that is capable of sourcing that, plus whatever overhead percentage you feel comfortable with.

 

[Richman]

I also read once where as a PSU gets older, the capacitance of its capacitors drops. Every year it suposedly drops some %ages.

 

[Tomas Liumparas]

Yes, but I've also read, that a PSU used below 20% or so to it's less efficient. How true it is? On the other hand, if it is used on let’s say 30% of it’s maximum power it should be way more cooler, basically just chilling so generally it should last more?

Here is a bit of my calculations I would be glad if someone could take a look and tell me if I am thinking right:

Server Board S1200V3RPS – max TDP 95W
XEON E3 1230v3 – max TDP 80W
Let‘s say 8 HDD‘s x 15W - 120W(I do not really know where I got these values, I just believe it is safe to leave this much for them?)
Some other stuff might use power – X W

So in total – 265W
I would like that my PSU would not exceed 50% of it‘s maximum power, so let‘s say I double 265w =530W
So let‘s say I then would like to buy 550W PSU.

Isn‘t it a overkill? Why? Well in my opinion CPU would usually use until 50% of it‘s TDP, I do not know about MOB but I believe it would not use 95W every single minute too.
Am I right? Or am I about to buy a way more powerful PSU than I actually need?

 

[Dusan]

Yes, but I've also read, that a PSU used below 20% or so to it's less efficient. How true it is?

It's very true. Check the graphs here: http://hardforum.com/showthread.php?t=1575419
And this review: http://uk.hardware.info/reviews/468...ery-low-loads-which-one-is-the-most-efficient
You'll understand why is the Seasonic G360 a favorite here for low power builds.

Let‘s say 8 HDD‘s x 15W - 120W(I do not really know where I got these values, I just believe it is safe to leave this much for them?).

5W per drive is more realistic (the WD RED 4TB consumes 4.5W when reading/writing). The important thing are the amps the PSU can supply on the 12V rail(s). A drive needs about 2A to spin up (the WD RED 4TB needs 1.75A).

So in total – 265W

I reality I don't think you'll every see that system drawing more than 150W. It will idle somewhere around 55W.

So let‘s say I then would like to buy 550W PSU.

Isn‘t it a overkill? Why?

It is overkill. Get the G360. 360W is more than enough, you get 30A on the 12V rail and the price is right.

 

[Richman]

I was also going to say that it was overkill. I would have to concur with Dusan.

 

[jgreco]

I'm going to be contrary by saying the 550 is probably just fine, going larger would be overkill though.

 

[Richman]

;):D

I'm going to be contrary by saying the 550 is probably just fine, going larger would be overkill though.

But you said in another thread, 'I have all the money'. So, you may have to sponsor his electric bill.

 

[jgreco]

Actually I was just quoting what Bender says in that scene. I'm a notorious tightwad, though will spend what's needed to do a job right.

 

[survive]

Hi guys,

Take a look at this:

http://www.plugloadsolutions.com/80PlusPowerSupplies.aspx

You can look up some PSU's you want to consider and take a look at the efficiency of each one over the whole range of the PSU's output. Ideally you want something where your typical load is in the "fat" part of the curve.

Personally, the system in my sig draws about 150w on 120v when it's booting up. At idle it sits around 80w and maybe 120w when a scrub is running. A GS360 would be a great PSU to pop into the system....which I really ought to do one of these days.

-Will

 

[Richman]

Hi guys,

Take a look at this:

http://www.plugloadsolutions.com/80PlusPowerSupplies.aspx

-Will

Nice find. All that PSU comparison data all in one handy spot.

 

[jgreco]

It isn't actually that useful for comparisons as a lot of the supplies listed are not available to consumers, or no longer produced. Fine to check two candidate devices against each other.

 

[Richman]

Fine to check two candidate devices against each other.

'Checking two against each other' .......... is't that basically the definition of 'Comparing'?

 

[jgreco]

Operative word: "candidate." The site is just about useless for identifying candidate devices. Very hard to know which listed items are available at retail without putting each into Froogle or whatever. However, go to NewEgg and find two 80Plus supplies, then take the candidates to the 80Plus site to compare stats, that works.

Hence my very specific wording and use of the word "candidate."

 

[Richman]

Operative word: "candidate." The site is just about useless for identifying candidate devices. Very hard to know which listed items are available at retail without putting each into Froogle or whatever. However, go to NewEgg and find two 80Plus supplies, then take the candidates to the 80Plus site to compare stats, that works.

Hence my very specific wording and use of the word "candidate."

Yeh, that's exactly what I was saying in the first post at 94871 about comparison data.

Nice find. All that PSU comparison data all in one handy spot.

jgreco, Ever been accused of mincing somebody's words? You use a word processor kinda like a food processor. Does great job at mincing without all the heavy lifting.;):D

 

[survive]

Nice find. All that PSU comparison data all in one handy spot.

That's actually the site of the guys that do the "80 plus" qualification testing, so it might be advisable to remember that the tested units could be cherry-picked or otherwise not representative of what you can actually buy. That said, the data avaliable there, when combined with the generic reputation of the PSU maker should help you make a more informed choice. Personally I like Antec, Corsair & firmly believe you can't go wrong with a SeaSonic.

Here's a nice write-up of the SeaSonic G-360:

http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story&reid=313

The only reason I don't have one yet is I can't get past the non-modular wiring.

-Will

 

[Tomas Liumparas]

I've got some nice reviews about SeaSonic too. The thing is that I can get only a few outdated models from my local reseller.
Currently I am strongly considering Corsair CX430M

The price is good, however I've read some nice reviews about it.

 

[survive]

Hi Tomas,

They liked the Corsair a lot as well, but I consider the SeaSonic to be a class above it. That said, if the CM430 is what you got access to there's no shame in that PSU.

 

[Richman]

The only reason I don't have one yet is I can't get past the non-modular wiring.

-Will

Modular may be nice and all but then I am not a gamer and have never had a system that would utilize more than 500w even with 6 drives and about 10 USB gadgets plugged in. I don't think even at start up it would pull 400w.

 

[survive]

Hi Richman,

Modularity isn't about gaming, it's about not having to deal with the cables you will never use in the system. I'll never use a 6 pin PCI-e power connector in my filer, so I would rather stash it away rather than zip-tie it up in a wad and tuck it up on top of the PSU or something.

-Will