PSU for 1300-1400 Watts?

Smoerble

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Nov 20, 2012
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Hello all,
I am building a mining rig (yes, i am aware, that it will not be profitable, I am not doing this to make money).

It will have 5 graphic cards (280x) with 200-250 Watts each.

My question now is:
What PSU can I use for this? Is 1500 Watts enough when starting up the machine? What PSU do you recommend and why?

Any help is highly appreciated, thank you
Smo
 


PCPartPicker part list: http://pcpartpicker.com/p/YNiY
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1 question why 5 crossfire ?

Power Supply: EVGA SuperNOVA NEX1500 Classified 1500W 80+ Gold Certified Fully-Modular ATX Power Supply ($343.98 @ SuperBiiz)
Total: $343.98
(Prices include shipping, taxes, and discounts when available.)
(Generated by PCPartPicker 2014-02-11 08:09 EST-0500)

 

Smoerble

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Nov 20, 2012
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So maybe I should better go for two rigs, each with 3 cards, because I need only 850 Watts each then? Way cheaper PSUs plus a lot better availability in my country...
 
You can't use gaming power consumption to estimate the power requirements. Each AMD reference design Radeon R9 280X card will draw 50 Watts more when cryptocurrency mining than when gaming. Also each GPU is treated as an independent processor so CrossFire is not being used.



Cryptocurrency mining with five reference clocked Radeon R9 280X cards is going to require PSU that has a maximum combined +12 Volt continuous current rating of 122 Amps or greater and that has at least five 6-pin and five 8-pin PCI Express supplementary power connectors.

A 1700W PSU would be more suitable. You don't want to be drawing more than 80% of the PSU's rated power on a continuous basis because that will drastically shorten the life of the PSU or generate enough heat to trigger the PSU's Over Temperature Protection circuit.
 

hunter315

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Moderator
At a DC power draw of 1400W even at 90% efficiency you will have a sustained power draw of about 1550W, which is the capacity for a 15A circuit on a 110V power grid, your inrush current with a PSU that size will likely be quite significant too. If you are not in a country running 220-250V I would carefully check out the circuit you intend to run this on, make sure its using 12 AWG wiring, and make sure it is on a 20A breaker; otherwise you run the risk of repeatly tripping the breaker or lighting the wire insulation on fire. I would not do this in any apartment as most of them have pretty sketchy wiring.

You are also talking about an OBSCENE amount of heat pumping out of a 1500W load, more than most electric baseboards draw and they are designed to heat a room...
 

tcb1005

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Feb 11, 2014
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Now I know why Radeons are so hard to find lately!
 

Smoerble

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Nov 20, 2012
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Thanks for the help so far, I learned a lot (and will hopefully buy order my stuff tomorrow ;)).

@hunter: Very good comment, I did not think about this. I live in Europe, so we have 230Volts. But it looks, like I will use 2 PSUs instead of one.
 

Smoerble

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Nov 20, 2012
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Oh, one more question:
If I buy 2x 800 Watt PSUs, but the rig needs only, let's say, 1000 Watts. Will the PSUs consume 1600+ Watts or only the needed power plus a little overhead?

Thanks



.
 

hunter315

Champion
Moderator
The PSU only draws as much power as it needs from the wall, so if each one is providing ~500W they will each draw the power they need plus that lost to efficiency.

If a PSU was always consuming the full power draw it would have an atrocious efficiency at anything except 100% load.
 

Smoerble

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Nov 20, 2012
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Thanks hunter.

Sometimes I read, that people ask for specific setpus about the 12 Volt lines... on the other hand, it seems a lot people don't care about this... is this important in my case? If yes, what exactly do I need to check before ordering please?


 

hunter315

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