Proper Power Supply Sizing Guidance

[Bidule0hm]

Thread created here: https://forums.freenas.org/index.php?threads/how-to-measure-the-drive-spin-up-peak-current.38885/ ;)

NB: I've filled the circuit and captures parts but not the other measurement methods parts (right now I just want to go watch a TV show :P).

 

[MindBender]

I understand the difficulties in properly sizing a power supply. But where I have always thought that power supplies had horrible efficiencies under 20% of their maximum loads, a couple of people on this forum pointed out to me that many modern high quality power supplies keep an efficiency above 80% to well under 10% of their maximum load. This makes the selection a lot easier, because you want to go with a high quality power supply anyway.

I am guestimating my SuperMicro X10SDV-TLN4F mainboard with CPU and memory is ballpark the same consumption as the E3-1230v3 example in the opening post. I will have 5-8 drives, of 21 Watt each and unknown spin-up and idle consumptions. I'm pretty sure that setup will not go below 50 Watt idle in total, making the Seasonic SS-500L1U a good choice, with >80% efficiency at 50 Watt load. This guy has tested this particular power supply:
http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story&reid=276

I think it's smaller 400Watt sibling may be a good choice too, but may be cutting a bit close at peak load with full driver population. However, with power supplies offering better efficiencies at idle loads, there's no longer a reason to purchase the smaller one.

 

[jgreco]

However, with power supplies offering better efficiencies at idle loads, there's no longer a reason to purchase the smaller one.

Correct.

 

[MindBender]

Unfortunately, my 8-bay case doesn't accommodate the SS-500L1U I had selected for the job :(. So this U-NAS NSC-800 case is turning out a bit of a contradiction in terms: I houses 8 hot-swappable and 2 internal drives, but not a power supply large enough to feed them .

The maximum depth is allows for it 207mm (8" and a bit), fitting only a SS-350M1U, which would probably do the job, but with no room to spare when spinning up all 8 drives. Higher power versions fitting that size probably have other compromises. Anybody a suggestion what other brands I can take a look at?

 

[jgreco]

From what I've heard, the NSC-800 is just too much of a compromise in several different ways. It seems like it'd be the ultimate NAS chassis, but only if the manufacturer carefully integrated a C2750, cooling, and power supply as part of the design, or there was some proven set of parts that would be suitable to the task.

 

[MindBender]

From what I've heard, the NSC-800 is just too much of a compromise in several different ways. It seems like it'd be the ultimate NAS chassis, but only if the manufacturer carefully integrated a C2750, cooling, and power supply as part of the design, or there was some proven set of parts that would be suitable to the task.

After receiving the case, I agree with your. But it's too late to send it back now and it's not really that bad, so it'll have to fly. I'll write a small review on it later.

Anyway, the heaviest power supply I could find to fit this case is the SPI FSP400-60UAP (http://www.sparklepower.com/pdf/IPC/FSP400-60UAP.pdf). It's 400Watt, not too much too spare, but I'd dare that if there's no alternative. And it's an 80Plus Platinum, so no slouching there. I just wonder who calls his company SparklePower... I've never hear of them, but designing an 80Plus Platinum PSU of 400Watt is no small feat, so I'm giving them some credit there. If only I could buy it somewhere in Europe...

 

[jgreco]

Sparkle Power is the retail label arm of Fortron. Fortron Source Power (the "FSP" in that part number) has been around for over 20 years and is the actual manufacturer for a variety of name brand power supplies such as Antec and Thermaltake. Also, if you've ever owned a laptop, there's a reasonably good chance that they might have manufactured the power supply brick.

Anyway, the heaviest power supply I could find to fit this case is the SPI FSP400-60UAP (http://www.sparklepower.com/pdf/IPC/FSP400-60UAP.pdf). It's 400Watt,

Maybe something like the AthenaPower AP-U1ATX50 500W 1U PSU?

Not a guarantee of compatibility, but if the only limitation is sub-230mm to fit the U-NAS chassis, I would think there's lots of options.

 

[Harsesis]

Just for the record: I have crunshed some numbers again and decided to go with an seasonic platinum 860W PSU (same price the X-series 850W here).

 

[MindBender]

Maybe something like the AthenaPower AP-U1ATX50 500W 1U PSU?

Not a guarantee of compatibility, but if the only limitation is sub-230mm to fit the U-NAS chassis, I would think there's lots of options.

Thank you for the suggestion, but unfortunately that one doesn't fit either.

I have opened the case now, and the studs I thought were the end stops for sliding in the PSU are in fact treaded mounting posts. A PSU can easily go over them, but that would leave no room for the cables to come out. So I have to stick with <207mm.

The main board does seem to support staggered spin-up, but I'd rather not depend on that.

 

[solarisguy]

[...] The main board does seem to support staggered spin-up, but I'd rather not depend on that.

I use that feature. I have it set to one disk every 2 seconds in my HBA. It allows me to have a power supply that is 80-100W smaller than if I did not use that feature.

 

[INCSlayer]

The discussion is looking pretty cool. I need help to design a power supply.
I want to know what are main parameters to design an efficient power supply?
Also what are the main hardware components for the design?
Can you please help me to select the components?

This is a Forum for Freenas not a gathering of electricians you probably wont find that answer here and even if you do you should probably start your own thread about it.

 

[rogerh]

If it is a one-off you probably don't need to worry too much about regulatory requirements for efficiency and power factor. You do have to worry about EMC, if you want any radio devices in your own and neighbouring houses to work so an OEM mains filter is probably good, as well as a steel box, with suitable magnetic and conductive properties. Then you'll need some fast switching mosfets, and various inductors and transformer that you will probably have to design and make yourself. The rest is just routine electronics.
Edit: and lots of cut and try to get it to work over all loads and ambient conditions. I'd advise you to aim for a box about four times the size of standard one, fitting everything in a small space is tricky.

 

[danb35]

@JedNaus, it sounds like you have a school assignment or something. In any event, as you've been told, this is not the place for your question (and I really have to wonder what train of thought led you to register here, today, just to post this question here, on a forum that has nothing at all to do with your question). The forums on eevblog.com could definitely help you out, but you'll have to have a better question than "design a power supply for me" there, too.

 

[Bidule0hm]

Wait, just to be sure, you want to design a PC/server PSU from scratch?

Edit: Ah, I'm too slow...

 

[solarisguy]

Design? That is fairly easy. To build a quality one...

 

[mattbbpl]

Wait, just to be sure, you want to design a PC/server PSU from scratch?

Edit: Ah, I'm too slow...

That's hardcore. Not sure how someone would top it other than mining the copper themselves

 

[danb35]

Wait, just to be sure, you want to design a PC/server PSU from scratch?

"To bake an apple pie from scratch, you must first create the universe." - Carl Sagan

 

[Bidule0hm]

It'd be me I'd do a linear PSU... heavier and bigger but hard to beat on the others parameters...

 

[jgreco]

I use that feature. I have it set to one disk every 2 seconds in my HBA. It allows me to have a power supply that is 80-100W smaller than if I did not use that feature.

Yeah, just make sure they never spin down for any reason, because you've got to stagger them when they spin back up, and that's no fun to arrange.

 

[solarisguy]

Yeah, just make sure they never spin down for any reason, because you've got to stagger them when they spin back up, and that's no fun to arrange. :)

If I manually unplug them, then I would surely plug them back only one by one :)