Power supply assistance

[SamDamn]

So I'm gonna get about 5 XFX 390's soon with the purpose of mining Ethereum. I'm getting them at a decent price, hence my motive for getting into mining.

My biggest issue at present is getting the right PSU. I'm planning on using:

Mobo: Asrock H97 anniversary
CPU: Intel G1820
RAM: 8GB
Others: Powered risers - https://www.amazon.com/Fixable-Adapter-Flexible-Extension-Connector/dp/B00IMYODGS?ie=UTF8&ref_=cm_cr_arp_d_product_top

Now, for the PSU, I was planning on getting an EVGA 1200W Supernova (Platinum): https://www.amazon.com/EVGA-SuperNOVA-PLATINUM-Crossfire-220-P2-1200-X1/dp/B00KYK1CKI

But I've come to realise that it may be quite insufficient to support 5 cards. 

My question thus, is whether or not the above-mentioned PSU would be insufficient for 5 cards. If it is, would it be possible to use 2x 750w PSU's (Gold) instead? - http://www.newegg.com/Product/Product.aspx?Item=N82E16817438017

[spartak_t]

So I'm gonna get about 5 XFX 390's soon with the purpose of mining Ethereum. I'm getting them at a decent price, hence my motive for getting into mining.

My biggest issue at present is getting the right PSU. I'm planning on using:

Mobo: Asrock H97 anniversary
CPU: Intel G1820
RAM: 8GB
Others: Powered risers - https://www.amazon.com/Fixable-Adapter-Flexible-Extension-Connector/dp/B00IMYODGS?ie=UTF8&ref_=cm_cr_arp_d_product_top

Now, for the PSU, I was planning on getting an EVGA 1200W Supernova (Platinum): https://www.amazon.com/EVGA-SuperNOVA-PLATINUM-Crossfire-220-P2-1200-X1/dp/B00KYK1CKI

But I've come to realise that it may be quite insufficient to support 5 cards. 

My question thus, is whether or not the above-mentioned PSU would be insufficient for 5 cards. If it is, would it be possible to use 2x 750w PSU's (Gold) instead? - http://www.newegg.com/Product/Product.aspx?Item=N82E16817438017

What is the exact model of the GPU's?

[SamDamn]

At present, this one is most likely: XFX R9 390 - http://www.newegg.com/Product/Product.aspx?Item=N82E16814150729

However, I also have access to these (which I'd prefer because of the coolers): Sapphire R9 390 Nitro (1010mhz version) - http://www.newegg.com/Product/Product.aspx?Item=N82E16814202148

[spartak_t]

At present, this one is most likely: XFX R9 390 - http://www.newegg.com/Product/Product.aspx?Item=N82E16814150729

However, I also have access to these (which I'd prefer because of the coolers): Sapphire R9 390 Nitro (1010mhz version) - http://www.newegg.com/Product/Product.aspx?Item=N82E16814202148

The Nitro version draws about 250W on games and around 325W on tests so I assume that XFX version will not be much different. I'm not sure what will be their load while mining Ethereum, but it should be somewhere between 80 and 100%. I believe that you need 2 power supplies just to be safe. 1 x 1000W gold rated and 1 x 750W gold rated.

[SamDamn]

Thank you for the advice. How would I go about connecting two PSU's to the same rig? I assume the 1000w would be used to supply power to the motherboard and 3 cards, and the 750w for the remaining 2 cards. Do I need any special power connectors for it?

[Ayers]

i think you can do it with a single 1300w from evga, you just need to undervolt your 390 to -100mv so around 200w each at maximum, in this way you can avoid all the trouble with two psu, because i've read bad story about two psu and a h81 pro btc, when using double molex

[spartak_t]

Thank you for the advice. How would I go about connecting two PSU's to the same rig? I assume the 1000w would be used to supply power to the motherboard and 3 cards, and the 750w for the remaining 2 cards. Do I need any special power connectors for it?

I think they both require 1 x 6 pin and 1 x 8 pin connectors so you have to be sure that you can connect them all with the available cables from the PSU's.

i think you can do it with a single 1300w from evga, you just need to undervolt your 390 to -100mv so around 200w each at maximum, in this way you can avoid all the trouble with two psu, because i've read bad story about two psu and a h81 pro btc, when using double molex

That's the better decision, but I'm not sure if he can do it...

[SamDamn]

Are you referring to the 1300w Gold rated one here? - http://www.newegg.com/Product/Product.aspx?Item=N82E16817438011

My local vendor does not seem to have it in stock at the moment.

Are there any other PSU recommendations I can look at? My local shops seem to have a few Corsair, EVGA and Coolermaster PSU's, but most of them show that I need to email them to confirm availability.

[spartak_t]

He meant that you will need 1300W gold rated PSU. It doesn't have to be EVGA, but it has to be from a good brand.

[SamDamn]

Ah, I follow now. What are some good recommendations for 1300w PSU's?

Alternatively, another option would be to use the above parts (H97; G1820 and the 1200w PSU) for 4 cards. I assume that at ~250w load, the 1200w EVGA would prove sufficient if I leave the cards at stock voltages, or am I wrong in my assumption?

And then, I can maybe try and get another setup with the same Motherboard and CPU, and add 2 cards to that build for a total of 6. My question then is whether a 750w PSU would be suffice for 2 cards in a similar build? Assuming a worst-case scenario of 275w power draw on each card and about 150w for the Mobo/CPU/RAM - which is about 700w total.

Thank you for your assistance so far as well, it is much appreciated.

[spartak_t]

Ah, I follow now. What are some good recommendations for 1300w PSU's?

Alternatively, another option would be to use the above parts (H97; G1820 and the 1200w PSU) for 4 cards. I assume that at ~250w load, the 1200w EVGA would prove sufficient if I leave the cards at stock voltages, or am I wrong in my assumption?

And then, I can maybe try and get another setup with the same Motherboard and CPU, and add 2 cards to that build for a total of 6. My question then is whether a 750w PSU would be suffice for 2 cards in a similar build? Assuming a worst-case scenario of 275w power draw on each card and about 150w for the Mobo/CPU/RAM - which is about 700w total.

Thank you for your assistance so far as well, it is much appreciated.

Basically you need to have about 15-20% difference between the power consumtpion of your computer and the PSU specs (i.e. if your total power consumption is 800W, the PSU should be 1000W).