Power Supply A Guide to 12V PSU

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Shrink Ray Wielder
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Nov 1, 2015
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Someone do it already :p

Run both DC PSUs in parallel from the same AC power source, and have one dedicated to the GPU's 6 pin power and the other for the rest of the components?
 

Kmpkt

Innovation through Miniaturization
KMPKT
Feb 1, 2016
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Two in parallel, single output to Dynamo 360/Dynamo Mini/HDPlex 400W etc and split power out from there. I plan for these to be 24V, not 12V as conversion will be ~2% more efficient giving me additional headroom for convection cooling. I also don't want to reinvent the wheel on my DC-DC PSUs.
 
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aquelito

King of Cable Management
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Feb 16, 2016
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Thanks. No fans, HDD running after system shutdown ?

As you may know, I had a small load switch developed to power off/on a GPU simultaneously with the system.

I wonder if such a device would be needed for the CPU 4-Pin or 8-Pin connector (would the system boot at all if connected ?).
 

Thehack

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Thanks. No fans, HDD running after system shutdown ?

As you may know, I had a small load switch developed to power off/on a GPU simultaneously with the system.

I wonder if such a device would be needed for the CPU 4-Pin or 8-Pin connector (would the system boot at all if connected ?).

Most systems boot for a split second but then turn off if missing CPU 12V. Not sure if it would latch the 12V properly if you do it at like that.
 

Valantar

Shrink Ray Wielder
Jan 20, 2018
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Hi everyone, new to the forums here (well, I've visited a bit, but never registered before!), so please don't execute me if I seem to be hijacking this thread entirely. I'm not trying to! :) Just thought this was a better fit than opening a brand-new thread.

I'm looking at building a custom enclosure for an APU-powered HTPC at some point in the future. I'm working with a relatively restrictive budget (not fixed, as this is early planning stages, but the key word is cheap), which isn't helped by VAT and import fees on anything costing >$40 ordered from outside of Norway. I was looking at doing a PDCB+external brick setup, but the cost of >100W power bricks of any kind of quality put me off that. So I started looking at internal 12V ac-dc PSUs, and came across the Mean Well LRS-150F for a very attractive price. It's from a different series than the open-frame versions discussed here, enclosed (which eases my mind quite a bit!) but well enough perforated to cool easily, but it also lacks PFC (hence the low price, I suppose?). It is the only 12V AC-DC unit I've found for sale in Norway for an acceptable price.

My question is rather simple: can I use this in a PC? Its voltage ripple spec is (rather significantly) outside of ATX spec (150mV p-p), but according to MW's own test report*, actual ripple under full load is only ~28mV - well within spec. Everything else from the report (that I'm able to comprehend, which is definitely the main limitation here - I'm no engineer!) seems great, from hold-up time to rise time, load regulation, protection, inrush current, reliability and efficiency (87.5-88% at 20-100%, 86.5 at 10%).

The PC definitely won't draw 150W, as it'll (most likely) consist of an ITX motherboard, one of the new Raven Ridge APUs, two sticks of RAM an m.2 SSD and a fan or two. I'll probably want to push the integrated graphics a bit for some half-decent gaming performance, but seeing how even the Ryzen 5 2400G is a 65W chip, I doubt the entire thing will draw much more than 100W under full load. I could probably scrape by with a 100W unit, but I like to have a capacity buffer for the sake of reliability.

Am I way off here? Will I burn my house down? Is the lack of PFC a deal breaker?


* had a link to it, but apparently new users can't post links - oh well, it's on their product page for the LRS-150F
 

Kmpkt

Innovation through Miniaturization
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I wouldn't roll the dice personally. Meanwell EPP 200-12/24 can be had for like 30 USD and has been used successfully by a number of people here. I'm sure the lower wattage versions would be cheaper.
 

Valantar

Shrink Ray Wielder
Jan 20, 2018
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I wouldn't roll the dice personally. Meanwell EPP 200-12/24 can be had for like 30 USD and has been used successfully by a number of people here. I'm sure the lower wattage versions would be cheaper.
Hm. That's a bummer. I can get the 100W version, but nothing beyond that sadly. I suppose it would theoretically work, but I'm not a fan of running the PSU near peak output for any significant amount of time. Unless there's an international store selling the EPP-200-12 with free shipping to Norway, I'd rather buy locally to avoid the import hassle (yes, shipping costs count towards the taxable total, for some inane reason. So a $30 power supply with $15 shipping would end up over $70 total when VAT and the customs processing fee is added).

After an hour or two more of navigating the (seriously badly categorized) site of the biggest Norwegian electronic parts retailer, I've come across a few different possible alternatives (with PFC), but sadly none with the excellent efficiency and tiny size of the EPP series. There's the PPS-200-12, which I can't find it on Mean Well's site, weirdly, but it's an open frame model with PFC and 150W passive/200W fan-assisted output. I also found the HRPG-200-12, which has a nice form factor, an enclosure, and screw terminals, but again low efficiency compared to the EPP-200-12. Not to mention that the extra output headroom would be nice should I ever want to move this to a build with a low-end GPU. I sent an email to the store asking if they could get the EPP-200-12 if I wanted it, I guess I'll see what they say. I found the EPP on eBay for $34 with $22 shipping, so I suppose convincing the seller to bill me separately for shipping would be the cheapest solution overall.
 

Valantar

Shrink Ray Wielder
Jan 20, 2018
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Mouser Norway doesn't work? 55 USD equivalent still seems fair?
Already checked. To quote the spec page:
Mouser said:
Delivery Restrictions:
Product available only to OEM/EMS Customers. Product is not shipped to consumers in the EU.
While Norway isn't in the EU, we're in the EEC, which generally means the same thing in terms of trade regulations.

Besides, unless Mouser has a fulfillment center or some such here, they ship from outside the country, which means the same VAT hassle. That their shopping cart page says "Duty, customs fees and GST collected at time of delivery." doesn't exactly instill confidence, even if they were willing to sell it to me.

Oh, if only it was that simple.
 
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Kmpkt

Innovation through Miniaturization
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Any chance you're travelling soon? Small enough that it would be easy to smuggle in. Alternatively you could have one of us mail it to you with an absurd undervalue : )
 
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Kmpkt

Innovation through Miniaturization
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Question about the Eurozone: do these tariffs etc. only apply to products that originate outside of the Euro? I was watching a really fascinating bit on the Estonian E-residency program yesterday and was thinking it could be invaluable for distribution in places like Norway.
 

aquelito

King of Cable Management
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Feb 16, 2016
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Already checked. To quote the spec page:

While Norway isn't in the EU, we're in the EEC, which generally means the same thing in terms of trade regulations.

Besides, unless Mouser has a fulfillment center or some such here, they ship from outside the country, which means the same VAT hassle. That their shopping cart page says "Duty, customs fees and GST collected at time of delivery." doesn't exactly instill confidence, even if they were willing to sell it to me.

Oh, if only it was that simple.

I guess they have a different policy in France. They sell to consumers and shipping is incoterm (custom duties already paid).
 

Valantar

Shrink Ray Wielder
Jan 20, 2018
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I guess they have a different policy in France. They sell to consumers and shipping is incoterm (custom duties already paid).
Any chance you're travelling soon? Small enough that it would be easy to smuggle in. Alternatively you could have one of us mail it to you with an absurd undervalue : )

I guess this is one of the consequences of being outside of the EU, but inside the EEC: we have our own import taxes and tariffs. I suppose we probably wouldn't be allowed to if we were in the Euro zone, given that that's supposed to be essentially a single economic zone in as many ways as possible. On the whole, I'm not opposed to our system - it definitely protects small Norwegian businesses from being out-priced by competitors 10x their size or more, a definite necessity to avoid monopolies in a country of only 5 million people - but it does kind of suck when you need something that no-one actually sells locally. I'd gladly pay the VAT on anything if that was the only extra, but when exceeding the limit also triggers "customs processing fees" from whoever is bringing it into the coutry (DHL, UPS, whatever) of $15-20 and the VAT calculation includes shipping costs (which, again, is absurd, as you're not "importing" shipping) suddenly you're paying 2x the price for something that was relatively cheap to begin with. But enough of the political mumbo-jumbo.

Buying while travelling would definitely be an option, but my only plans for this year is a trip to Vietnam and Cambodia in the summer. Doubt I'll be able to find this specific PSU there during a holiday where I'm constantly moving around :p

The funny thing is, technically, undervaluing wouldn't even be necessary given that the product cost is below NOK 350 ($44.46 according to Google) - in that case the shipper simply needs to not include shipping costs on the attached invoice. Marking the shipment as a gift on the customs label also bypasses this, no matter the value. The problem is that most serious sellers won't do either (customs fraud is usually frowned upon, after all).

The good thing here is that I'm not buying anything any time soon, so I have plenty of time to figure this out :)

Question about the Eurozone: do these tariffs etc. only apply to products that originate outside of the Euro? I was watching a really fascinating bit on the Estonian E-residency program yesterday and was thinking it could be invaluable for distribution in places like Norway.
As Norway is outside of the Euro zone, this doesn't apply. If we were inside, we wouldn't have the import tariffs that we do now. As it stands, the law is quite simple: private import of any consumer good from outside of Norway, regardless of origin, exceeding a value of NOK 350 including shipping on the customs declaration requires paying VAT upon passing customs. Shipping companies then charge rather ridiculous processing fees on top of this. I don't mind the VAT payment at all, but it really ought to exclude shipping. Paying shipping companies $15-20 for processing this is absurd, and adds massively to the cost of otherwise cheap items.
 
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Thehack

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Fits like a glove.