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I am considering spending almost $1,000 on 3-4 gold rated PSUs.

Seems to me they are little more than transformers.

If I could purchase 4*$30 PSUs simply to run the motherboard/cpu power... could I note create a massive single 12 volt rail that distributes power to say 30-40 video cards via pcie connectors at once?

I guess it would really suck if THAT power supply broke down... but still - anybody tried it or similar?

Not to be a jerk, but that sounds like a really good way to kill yourself. Playing with 10+ amps is not a good idea.

Yes PSUs are transformers, but they're also filters and some other stuff.

No offense taken! I don't know much about electricity yet... but it sounds like a pretty simply job.

That's the last phrase of someone gunning for the Darwin award.

Seriously, playing with electricity that contains enough amps to kill you outright is NOT something that is recommended, unless that is your job and you've got education to back it up.

Famous last words  ;D

1) go and get yourself trained for electial work
2) then think about what you're doing
3) buy relevent PSU's
...

in other words - don't .
please it's not worth it - you'll kill yourslef , burn the place down and kill others.

Well... it's not :P. A simple 12V 2A power supply is no problem, even for beginners, but these high amounts of currents require serious designs.

Not at all, ampere don't kill you. Even heard about someone being electrocuted by a car battery? I guess not. And you can easly get hundreds of Amperes out of them

Electricity starts to be harmful at about 50 Volts.

BTW, PSU are not transformer, they are AC/DC switching units (note the plural). You can't just connect some of them together, you'll just end up frying all your hardware.

It SOUNDS simple yes but that's merly because you don't know anything about it... Don't throw yourself at it because:
First of all it will take at least a month to just read up all the theory behind (and that's assuming you're damn smart)
Secondly there's a huge bunch of safety hazards
Thirdly it's a huge investment because quality capacitors aren't cheap and you'll need that for 24/7 operation

Last but not least: It's MUCH more difficult to build a big powersupply rather than a lot of small ones...

Moral of the story? Don't waste your time on it

Here is a look inside a high grade high watt power supply:

http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story4&reid=189

still not convinced? have a look at this ;) http://www.pavouk.org/hw/en_atxps.html

What the crap are you talking about? 100mA can stop your heart. Why would people go around being electrocuted by a car battery? I turn my car on with a key, not by shorting the leads with my body.

And yes, PSUs are transformers, at least functionally and they incorporate transformers as well as power switches. As I said they are complex creations and not to be made at home.

Yes, 100 mA can kill you. But, to make that current to flow thru your body, it needs to have a given potential (because, as you will know, our body is not a good conductor). Depending on a lot of factor (skin resistance, humidity, position of the electrodes,...) the voltage that can kill you starts from 50 VAC at the very least, and goes up to several hundreds. You can't even feel anything if the potential is only 12 VDC, disregarding the maximum current that it can generate.

Expensive PSUs offer greater efficiency. Considering our purpose, it would be stupid to pay 100$ less for a PSU and pay 50$ more every month in electrical bills. Not only that, but you need a PSU that offers:
- the required power drain
- filtering and leveling depending on external supply and internal PC power usage
- protection of itself and PC components in extreme cases

Would you pay 100$ less for a PSU and risk destroying your 900$ video cards at the next brown-out?

PSUs take a lot of time and skill to design correctly, and to use quality parts.

I was at a local PC parts retailer recently and saw someone walk in and ask for a SHAW brand 680 watt power supply for $17, while I was buying a Cooler Master GX 750 watt for $115 for my bitcoin set up.  Over six times the price for just a little more power?  You'd think I'm crazy to pay that, right?  Well, the Cooler Master will actually deliver its rated power, with high efficiency, stable voltage and current, into multiple voltage rails and do that for years to come.  The SHAW will do none of that, and likely blow up (not joking) and take the customer's other PC parts with it.

The moral of the story is high quality, high current power supplies cost more because they are so much better than the cheap brands and certainly anything you can build yourself (unless you're en electrical engineer).  

Follow the advice of other forum members and please don't attempt to dismantle or build your own PSU.

actually 25mA of current has to go through your heart to stop it. knowing that the human body has a resistance of couple of Mohms(lets use 1 for the equation although is kinda bigger) the equation I=V/R is I= 12/1000000 = 0.000012 Amps of current in your body. that wont kill you, it will only make you stronger ;) :P

Seems in line with them miners on these forums that have their motherboard running on the carpet with fans blowing into it and all that.

Bitcoins get more expensive everytime there's a big story somewhere. A bitcoin Death would really help us get out this 25 / 30 USD lameness we're in.

Take one for the team!

Hey here's some advice; if you're looking to join multiple rails together, some PSUs have an option they like to call turbo that joins together all of its 12V rails.  However, I've heard that running on single rail too long will often cause the PSU to die prematurely on high loads.  I know my Tagan can do it, but it's just 800W.

Here's a multi-rail 1200W system http://www.newegg.com/Product/Product.aspx?Item=N82E16817371043  It'll handle just about anything you throw at it.
Here's a single-rail 1200W system http://www.newegg.com/Product/Product.aspx?Item=N82E16817171055  It'll handle what you want too, but any energy spikes you get will go through the whole system.

I had a HDD cause problems with my DVD burner a while back because they were on the same rail and the DVD burner was having power spikes on writes which was causing failed burns.  Putting them on separate rails allowed for steady current to my burner and my burns came out nearly flawless.  So I recommend multi-rail for high-pull hardware.  Just be sure that the specs allow the wattage it needs per rail.  12V * Wattage per rail = output per connector line.  The above should handle around 3 HD6990 cards unofficially without problem and leaving 300W for the rest of your system.  It's cutting it close, but I don't imagine your CPU using more than 150W on an i7 and newer HDDs will use about 11 watts max so you're good to go.
Don't go thinking that the loss in available power per rail makes it less efficient.  The fact is that you'll probably never need 360W on a single rail anyway so the other rails can more than handle the loads on their own while mitigating power spikes making it more efficient on the PFC side of things.

power supply is not something simple.. i have studied electronics for 3 years in high school and computer related electronics is not "simple job". psu is devided in 2 groups in the circuit, 1 side high voltage and 1 side low voltage, and there are lots of chips involved. so don't even bother programming chips, its pain in the head, believe me. :)

I looked at the viability of doing something similar, using 48 volt telecom rectifiers as a PSU (but flipping around the ground reference, because they're all negative voltage).  They deliver substantial current on the cheap (200a at 48v, so 800a at 12v if you run them through a bunch of big ass batteries).  But at the end of the day you will have spent 1k on batteries and regulators, plus cabling, plus capacitors and diodes, yada yada yada.  By the time it's all over, you'll end up with 1.5k worth of crap, and a whole bunch of work, just to power up your "30" video cards, with a single point of failure, and a bunch of electronics that are hard to understand and hard to work on.  I looked at other options, like inexpensive 12 volt battery chargers, no dice.. they're too expensive.  The cheapest option you have is the $1000 worth of PSUs.

By the way, I read your other thread about the smoked components.. I've got a pretty good idea of what happened and why, based on a critical omission on your part while describing your setup.  Of course I'm going to be a troll and not reveal what it is, both because it's already been asked/answered on the forum at least once that I'm aware of, and because I'm not going to help anyone devalue my investment in mining any further by making it any cheaper for you, or anyone else, to do business.  Knowledge is power, and when you don't have it, sometimes you have to pay for someone else's, i.e. in the form of those expensive PSUs.  That smoke should make you less bullish on playing with fire, not more.


He seems pretty determined to do so, doesn't he?

Depends on which side of the switching circuit you decide to poke your fingers into. The 12V on the business end might be safe, but what you get from an unregulated discharge of the capacitors on the other end is a whole different story. Probably one with a sad ending.

Your a fucking idiot, i can take 20,000 Volts and be fine, It'll hurt like FUCK, and theres a small chance it could stop my heart if exposed for too long.
But a fucking 5v USB Imput slot can kill you because of the current.

Have you thought of using multiple smaller PSUs you can get them alot cheaper under 900 watts

the voltage has very little to do with it.  it's the current that matters.

a 20,000 volt static discharge is only a few milliamps, while the 5-10 watts available in a USB plug is 1-2 AMPS.
so why arent people electrocuted by USB plugs ?

the resistance of human skin, at 5 volts, is very high, therefore very little current will flow through the body.

It's basic ohms law.

This is what happens when you mix electricity+unknowledge : http://www.clipaday.com/videos/pen-trick-gone-wrong (http://www.clipaday.com/videos/pen-trick-gone-wrong)

Thanks for the backup!

It's like saying that, in a engine, torque has little to do with power, it's the RPM that matters.
You can easly jump from current to ampere knowing the resistance (or better impedance) of the load (human body) and of the generator and vice-versa.
In those 100'000V devices, the output impedance is so hight that even slightly conductive loads can drastically cut the output voltage. Cutting the voltage = cutting the current.

ehhhhhhhhhhhhhh your half right

I'm pretty sure i'm 100% right, do you mind pointing out what's the 50% wrong part of what i wrote?

I'm pretty sure you are too, but ohms law is hard, let's go shopping for more 6990s.  NOT!

I think you have yours backwards.
if we are comparing an engine with rpm and torque, the the rpm is like voltage, and torque is the current.

and this is true, RPM's have almost nothing to do with torque
ie an electric motor that can produce all of it's available torque at .0000001 RPM
or a fan spinning at thousands of RPM that you can stop with a finger.

The real answer in electrical safety is that it takes a combination of sufficiently high voltage, current, and the proper waveform to kill you. 240V mains is nearly ideal for this.

A van-de-graff generator can produce very high voltages, and high current pulses, but has a very low RMS power and averaged current, and is thus safe.

5V USB or a car battery can produce a lot of current with a steady DC waveform, but lack sufficient voltage to produce much current in the body.

Tesla coils can produce hundreds of thousands of volts at reasonably high currents, but operate well into RF, and are thus a serious burn hazard but leave the heart electrically unaffected.

120V mains will generally not kill you, but has a low enough frequency, high enough voltage, and high enough current that I can if you become entangled with the source and are unable to get free.

I hope this has cleared up some pseudoscience.

Also building your own PSU is not outside the realm of an advanced hobbyist, but you are much better off simply buying them given all the design and build time required. If you want to save some money, look for secondhand PSUs.

Source: electrical engineering student and high voltage enthusiast

The PCIe bus spec only allows 30watts per slot, thats why most higher end video cards have external power connectors on them.
Sure, you probably could bridge together enough cheap power supplies to power all those cards. Or, come up with one really big 12V power supply capable of handling 100's of amps.

The problem with lower quality power supplies is the power you will get out of it then will have ripple, and inconsistent voltage regulation which will make bridging more then a few cheap supplies together difficult, since they will not supply current evenly across all the supplies.

A single very large supply has the other problem that it requires very thick cables, or copper buss bars to distribute all that power to the cards.  Ciopper buss bars carrying hundreds of amps are dangerous at almost any voltage, and require regular maintenance to maintain good connections to prevent excessive heating of the buss or connectors.

I wouldnt risk thousands of dollars in GPU's connected to a makeshift 12V power supply, it's just not worth it.

Actually, powering ~20 GPUs off something like this might be quite a good solution for large mining farms: http://www.alibaba.com/product-gs/436983856/_YK_AD10KW_10kw_dc_regulated.html

It compares quite well to a computer PSU, and would cut costs a good bit for large scale miners.
--Efficiency of Whole Body: ≥86%. Source Voltage Regulation:
--Voltage-stabilizing ≤0.2%. Load Regulation: ≤2%; Ripple Voltage: ≤4%

While this seems like a dick move, I can at least understand why you feel that way.



This is what I don't understand.  The guy simply asked the viability of making his own PSU's to supply power to the 6-pin PCI-E video card slots only.  (not entire systems which require all the chips / circuitry / logic)
It was a simple question of "would this be something I could do?", and that response of yours is acting like he said "fuck all you imma do it anyway"

"Don't try and build your own power supply" has just become the 20th safety tip. gigabytecoin, you are the ballsiest miner out there, care for an interview while you're still in one piece?

Who'd a thunk this would have caused such a stir??? :P

Went and bought a few OCZ 1250W Golds... thanks for the advice gentlemen!

I'm glad we heard back from you - I thought you tried this and roasted yourself.

Damn guys, if www.xtremesystems.org was up you'd be in for a TREAT, one of the enthusiasts there built his own 2000+ watt PSU, it was EPIC /sigh another day :P

I, personally, have taken 100 kv hand-to-hand intentionally. I was fine. Didn't hurt at all.
Then I burned a pinhead-sized hole in my finger with the arc I drew while moving the electrode away from myself. That hurt a bit more. Healed right up, though.
The PSU in question was a lamp ballast. Ultra-low current (microamps.) I was using it for a mini solderbot.

I've also accidentally touched a 300v flash capacitor. I woke up on the couch with my parents looking down at me in horror. (That was for a portable EMP cannon.)

And I've also played with a gigantic capacitor bank (megafarads!!) at 1 volt. It vaporized the electrodes.

Electricity is not some magic dangerous thing. If you understand it you can be safe with it.

(oh, and don't build your own PSU. if you fuck up you'll kill your graphics card, possibly the mobo as well)

even 30amps 12v dc wont kill you that's all I wanted to say.

Actually what he asked had to do with ganging up small PSUs in order to make, effectively, one big one.  That's incredibly simple - you need nothing more than a bunch of diodes (albeit, big ones) and a bunch of soldering.  But then what if current-hogging ensues because you didn't know to include components to equalize the voltage between the various PSUs and they start dying right and left?  If the OP doesn't know what a P/N junction is, how a diode works, what forward/reverse bias is, etc., then how would he know how to fix the inevitable problem that pops up when there is one?  How would he know how to fix the design flaw in my aforementioned example, or other unknowns?  As for "fuck all you imma do it anyway", that's what it seemed like.  The question was essentially phrased like.. "I wanna do this, tell me how!"

Yea you could.

But I think it's a lot easier to just bunch a few smaller PSU on a few Systems. It'd be a much easier system to set up, Safer, lesser point of failure. It'd have less of all the problems that were mentioned and more of the benefits that was perceived.

I really don't think that you should even be considering undertaking a project that forces you to ask "Uhh, just how much of this can kill me? What are my chances of survival?"

Honestly, just buy the PSU's. I've never EVER heard of someone building their own.

Actually, it's impossibile to make 30 amps of current flow thru you with only 12V. That's what I'm trying to tell you all: there's this thing called "resistance".

but yes, If you could, It would kill you.

Well yea I built my own power supply for equipments that are use in industrial areas a while back (when my uncle began to cut cost -.-), he paid me close to nothing for the electrical/electronics degree I own. So I know with good planning, precaution and safety into the design, this is definitely possible (even w/o). But I just think it's not recommended.

Can you stop arguing about the amps and the health concerns? You don't wear your home-made PSU on your head do you? Just don't touch the case and use a good grounding, no danger, end of story.

Now, resuming. Does anyone know if you can integrate a solar array with an UPS and PSU to have the highest efficiency between the components?

The best method I know:

1. Order a "fully modular" PSU.
2. Once it arrives plug in all the proper cables in proper holes on the sides of the PSU
3. Profit!

this

it would take some serious effort to build a psu (from scratch) maybe if you found a schematic of a unit that someone had already built and tested.

Lol thanks for the kind words ;)

I built a power supply for some specialized equipment I built while working on my Physics PhD.  You can easily find the relevant info on how to build a good power supply.

But it is terrible waste of time and money.  You will never do it cheaper than the box you buy from commercial supplier.

It is more than just a transformer (though that is most of the weight).  It is also a diode and a filter.  High current versions of these components are expensive.  Also you will spend a lot on all the little extras, the box, the heat sinks, the switches, the connectors and the cables.  The cables and connectors have to be well made, a lot of failures happen because of bad cables.  Each card requires 6 separate power feeds each with it's own ground, that's twelve wires per card.  If you buy a power supply it comes with the cables!

For building my rigs I went with the best power supplies I could find.  I've built four rigs and spent about $850 for the four supplies.  My first two were 1200 Watt supplies (Antec, on sale $217 each) and I realized based on experience that that was more reserve than needed so my last two supplies were 850 Watts (Corsair $189, Thermaltake, $229) and that seems to be enough to power 4 5850 cards.

Sam

PSU is both a transformer and AC/DC switching unit. First you need the transformer to get to proper voltage, then you put in a transistor bridge, few diodes etc. and you got yourself DC. I also would recommend a regulator and few small capacitors and low Ohm resistors, and a heatsink for the regulator(s). The combination of regs, capacitors and resistors should filter everything out :)

Working with high amperage low voltage is safer than high voltage low amperage IMHO, because the electricity does not "jump" as easily. High voltage is needed for being able to go through highly resistive materials (see Tesla coils for example. That's also why engine spark wiring insulation is such an important factor). My hobby used to be RC cars, and i had 7.2V 400A peak battery packs... I was more worried about getting them pierced while driving (and resulting explosion & fire) than getting a shock.

Here is how you can build it:
http://engknowledge.com/power_supply_design.aspx

I would design it to be quite parallel, meaning multiple transformers, multiple bridges, multiple capacitors etc etc.
So that any single component has smaller impact if it fails on operation, or is otherwise flaky. I would design regulators, capacitors etc. well beyond required spec to reduce risk of failure.

Also, doing it from this low level you could add some basic electronics to handle backup power, see for example: http://www.dreamgreenhouse.com/designs/12v/index.php (links to their UPS project),  http://tech.icrontic.com/articles/super_ups , http://1wt.eu/articles/alix-ups/

Last one is the most intresting one infact :)

Google is your friend, but i wouldn't suggest trying this with no past experience on the required scale....

I accidentally shorted out a li-po.... Fortunately, it iddn't explode, because the wire got so hot that it failed! Into salt-water it went... :(

A waste of ~2BTC!

My man, don't forget a good surge protector/suppressor, or a backup power unit to go with your PSU.  You gonna think your system as a whole, not just the power supply unit. 

Salt water is not good for draining a lipo. A lot of times the the salt water will corrode the tabs, breaking the connection. This makes the pack seem like it has 0 volts when in fact it does not. Best method to dispose of a lipo is to hook it up to a small light bulb and let it drain to zero volts. Then twist the positive and negative leads together and toss in the trash. Of course let it discharge in a fire proof area.

Or the more fun route is to drive a nail through the pack and watch the sparks fly!

BTW, while not actually building a PS, I'm thinking the following server power supply would be a good candidate to power a couple video cards on the cheap:

http://sites.google.com/site/tjinguytech/my-projects/HP47A

what about "volts jolt, amps kill"?

As someone who has been in the middle of developing motor controls (also DC switchers -- lotsa MOSFETs for the 200A@28VDC we were dealing with as our largest design), I say just buy a friggin' power supply.

There's a reason the higher efficiency ones cost more.  Everything with good efficiency probably has PF correction, and there are some sexy little chips that can basically take care of it for you (adding more switching, of course -- yeah!).  Basically, it's easy to design a power supply.  It's even easy to design one with pretty solid outputs.  Will it be cheaper?  Maybe, but probably not, and it's unlikely that you'll end up with a design that's efficient and if you want to you're going to put in a lot of effort to do what others have already done at pretty low prices.

An acceptable solution would be to use multiple cheaper or lower power PSUs, one for the system and one for each video card, all grounded on the same case. Some companies even sell modular supplemental bay PSU models for such a purpose (GPU only supply). The trick is to power on the secondary PSUs when the main PSU gives the "power good" signal.

http://www.newegg.com/Product/Product.aspx?Item=N82E16817104054

A little more expensive than an extra PSU, but its a lot cleaner, and allows you to hook it up to your PSU and turn off/on with the PC.

Power supplies that have a UL approval should deliver their rated output continuously without overheating. UL (which is owned by fire insurance companies) tests that. UL also requires that no single component failure can cause a fire.

Phony UL approval markings are often seen in products from China. But there's a way to check. UL has a database of approvals. (http://database.ul.com/cgi-bin/XYV/template/LISEXT/1FRAME/index.htm)  The UL file number on the UL approval sticker must match the manufacturer and the description of the item.

Here's what it takes to test a power supply. (http://www.hardwaresecrets.com/printpage/Hardware-Secrets-Power-Supply-Test-Methodology/522) Hardware Secrets connects the power supply to a load box, loads it up to its rated output, and runs it for hours at 45C while checking the electrical outputs. See their reviews. (http://www.hardwaresecrets.com/page/power/all)

You should buy the right stuff if you bought your hashing hardware and you care about how long it lasts on you

if you dont:

I used to do (and still do sometimes) dumb stuff like this too. I think the OP just wants to get more power up and running without having to spend a ton. Especially if you have a surplus of crap power-supplies already.

I work for a small custom computer assembly company, and we have shelves full of useless 300w cheap china crap PSU's that come with the cases we end up not using. they are sitting around wasting space. We use them for various personal purposes and testing and consider them disposable. They blow up, chuck it and grab another one.

check this link:
http://www.directron.com/2powersupplies.html

long story short, you can manually power up an ATX powersupply by shorting pins 14 and 15 on the 20 (or 24) pin primary connector.

If you want to rig up two power supplies for your computer, one for each power supply (or more if you are a lunatic) and power them up at the same time it *should* work. Or check the section where it shows you how to build a relay.

I would stick to one crap power supply per juice guzzling video card, 
if the powersupplies are very low quality do not run them at the rated load listed on them, stick to 50-60% (if it says 300w on the sticker and its a single 12v rail dont push it past 150)

I have a few Radeon 5770's and 4870's hashing, and I have had experience with running radeons with insufficent power. If the radeon looses juice from the 6-pin connector under a load, (has happened to me) the motherboard should error out and shut down the primary powersupply attached to the motherboard, some of the older ones also have wonderful beepers on them that will scream like a banshee if they don't have enough power. If you are in the building you will know it.

I take no responsibility for whatever crap you break trying to do this. There is a right way of doing things and the "get it done now for $0" way of doing things.

as for the health risks? Try not to lick the power supplies or any exposed wire leads while in your bare feet.

Good Luck

Please if you decide to build your own please PLEASE video it when you first power it up. :) :) :) :)

yep, great idea! Youtube revenue from great video of spectacularly blowing up a self made PSU could be higher than any possible savings you hoped to get by replacing decent and expensive PSU's.

Nou... because i reread it and you are 100% right but the metaphor threw me off

If you think you can design a better PC-type switching power supply, here's how to try.

Download LTspice (http://www.linear.com/designtools/software/), which is a circuit simulator optimized for switching power supply design. Take a look at the data sheets for switching power supply control ICs. (http://www.linear.com/products/switching_regulator) Read the application notes. Find some switching power supply transformers for which specs are available, and try to design around them. Don't forget protective circuitry. When you have a circuit that works in simulation, post your LTspice file.

If you're really good, you might be able to duplicate the performance of commercial design for 2x to 3x the price in quantity 1. PC power supplies are incredibly cheap for their power output. As a rule of thumb, industrial power supplies cost about a dollar a watt. PC supplies are far cheaper.

I've designed a switching power supply, but it was for a special application for which no off the shelf solution existed.



 

If you dont youtube this you will be commiting a bitcoin mining sin!

And will go to hell and stuff plz plz plz youtube it  ;D