Power supplies (specific and in general)

[onestyles]

Hello,

I have 3 USB Gridseeds running and am just now getting in to the whole mining scene as an enthusiast. The units are said to consume around 7 watts each in Scrypt only mode. I have a standard wall plugin (see picture) that I am using right now to power these and splitting off of it 4 ways. Is this a safe (non-fire hazard) way to run these, or should I be hooking them up to an actual power supply? On a somewhat related note, I have a Corsair CX500M power supply that is sitting around - if I should and/or do use this, is there any idea how many I could run off of it? My understanding is that it is not as simple as taking 500 watts and dividing by 7 (500/7=~71) and allowing some extra breathing room, so at least 50 could power off of it? My understanding is that this is oversimplifying it too much and there is more to consider?

I have seen people say that they use a specific power supply for this or that unit that they own, and I have done some looking online for this, but I haven't found a good source that gives an idea to the lay person exactly how they should calculate how much power usage they can or should use. Any tips or recommendations to either paragraph are greatly appreciated. Thank you!

(below image is what I am currently using for the 3 Gridseeds)

https://i.imgur.com/65STrWz.jpg

[kodeon.CEO]

I don't really know much about the miners you are using, I would not recommend the wall plugin as I'm not sure how safe they are and if it will damage any components. But I would recommend if you can having at least an 80+ gold certified ATX power supply for any mining set up if you are thinking of mining over the long term. (most of them should have all the safety features) and then calculate how much power you will need also if you are planning for any future expansion to calculate that as well. I would say you would want to leave about 15 - 25% breathing room for your PSU to be on safe side.

Basically I think you should go for your Corsair CX500M.

I'm sure other people will have their opinions but that's just mine, hope this helps.

[onestyles]

Hi kodeon,

Thanks so much for your response. If I picked up the right connections then, my 500W (only 80+ bronze certified) should be able to handle around (500x.75=375; 375/7=)~53 of the units at around 7 watts each.

I appreciate you chiming in!

[kodeon.CEO]

sounds good and sure no problem, good luck.

[leotheminer]

Hi kodeon,

Thanks so much for your response. If I picked up the right connections then, my 500W (only 80+ bronze certified) should be able to handle around (500x.75=375; 375/7=)~53 of the units at around 7 watts each.

I appreciate you chiming in!

That PSU has a single 12v rail @38A, which will give you 456W (max). Derate this to 80% or 365W available to avoid melting the lousy 12v wires on the thing.

[onestyles]

Hey leo,

Thanks for the very insightful response. Is it as simple as multiplying the amps to the 12v rail, then looking at the certification rating to determine how high to go?

So for example, this power supply would be recommended for up to around 800W? ( 12V x 83A x .8 )?   http://www.newegg.com/Product/Product.aspx?Item=N82E16817151105

I appreciate your thoughtful expertise on what is probably the last question    

[leotheminer]

That SeaSonic one you mention looks awesome. It's one of the new design class that draws the 3v and 5v rails (which miners typically don't need) down off of the single massive 12v rail, so you can use all 996 watts @ 12v.

It's super expensive though. You could have like 4 smaller ones for the price. But they wouldn't be very efficient. The good one is probably worth it.

[pmorici]

Check out the Gigampz threads about using breakout boards with server power supplies to cut your power supply costs.  Essentially instead of buying a whole bunch of little cheapo supplies for 30 - 100 bucks each you buy a adapter board and recycle an old industrial grade server power supply.  Total cost with shipping is about $70 or less per 850 / 1000 Watt PSU.  For miners working at scale the cost comes down even further.

https://bitcointalk.org/index.php?topic=622783.0
https://bitcointalk.org/index.php?topic=745017.0
https://bitcointalk.org/index.php?topic=652402.0