How do you deteremine how big of a power supply to get?

I am trying to understand how you decide how big of a power supply to use. You have to power the cpu, ram, motherboard ssd/hd if you use one. Graphics cards and pcie risers. I am confused because I read one person has a rig with 6 graphics card and the system with risers. And there using a 1000 watt power supply. How I ask?. There 6 GTX 1070’s with 150 watts each. The cpu, board and ssd. say 100 watts. Now the pcie risers which I read use somewhere between 40 and 50 watts each. That’s 1300 watts.

What I have is

cpu, motherboard, ram and ssd - 100 watts
7 - MSI GTX 1070 Gaming X - 1050 watts
1 - EVGA GTX 1070 SC - 170 watts
1 - Zotac GTX 1070 AMP Xtreme - 250 watts
9 - pcies ver7 risers - 450 watts
1 - Corsair AX 1200i
1 - Antec Quattro 1000
total - 2020 watts

Was planning on putting 6 cards and the system on the AX 1200i. And the 3 - remaining cards and 9 - pcie risers on the Antec 1000. Is this wrong? Am I wrong with my numbers? I may replace the Zotac GTX 1070 AMP Xtreme because of what it uses in watts 250. With another MSI GTX 1070 Gaming X. One last thing I plan on using Simplemining OS.

Thank you for any help making me understand this.

OS is great for rigs with same cards, if the EVGA and Zotac card have other OC settings you can’t set them singulary, you can only set OC to rig’s so only one OC settings for all cards of rig.
I get a steady 10 sol/s more with simplemining than windows (for each card)

Anyways, with power, the most important aspect is to not charge over the efficiency power level of the PSU, usually drops drastically after 90%. So having a PSU using 60% of it’s limit instead of 90% will give you a less power drawl overall.

I would never put 6 1070 on a corsair AX 1200i, max i would put 4, even thought 5 should be capable without hickups and with 6 you are likely to have some random drop rates from some cards (with low TDP you could keep 6 stable, but not good power draw).

Sell your Antec Quattro and grab a 1400 W or more.

Another important aspect of PSU are the cables. Remeber that you have to power 9 risers and 9 cards, so make sure you have all the right cables and/or solution (molex risers are not trustworthy enough, don’t power more that 2 risers with sata connection, etc).

If I remove the Zotac from this rig. And do it this way -

AX 1200i - 5 cards 150 watts ea. System and 3 risers - total - 1000 watts

Antec 1000 - 2 cards at 150 watts ea and 1 card at 170 watts. Plus 5 risers at 250 watts - total 720 watts

Would work for now? I’m keeping the Antec for now. It’s not used it a brand sealed I have had sitting for sometime. The Corsair brand new got it 1 1/2 weeks ago.

From my understanding, the GPU draw power through both the regular PSU cables (8pin/6pin etc.) and from the riser. A max TDP of 150W includes the power draw through both cables and riser. In this way, the card draws whatever it can from the main PSU cable and, if needed, draws the rest through the riser. So you don’t need to factor in riser power separately.

What is important, though, is that you don’t overload the connectors to the risers. If one GPU draws, let’s say 225W, and is connected through a single 8 pin connector (which is rated for 150W), then the rest (75W) needs to come from the riser. Regular SATA connectors will not support such wattage and can be a fire hazard. Most of your cards should have enough auxillary power connectors, and the power draw through the risers will be negligible (MSI should have 8+6pin rated for 150+75W, Zotac 2x8 pin rated for 2x150W). The EVGA card, though, only has an 8 pin connector rated for 150W. It then needs to draw at least 20W through the riser. I don’t know how each card balances the power draw between PSU and riser, and I would advice against SATA risers altogether (or SATA adapters). Use molex or 6pin risers connected directly from PSU, if possible.

Another thing is that you should connect each of the GPUs and its corresponding riser to the same PSU. You don’t want that a card is powered from different PSUs, as it can supposedly lead to trouble. So don’t put risers on one PSU and the GPU on another.

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So then if I ran 6 1070’s on the AX1200i and pcie risers, the system it would use 1000 watts, right? That so that would leave 200 watts not used from ps. The person above you said never run 6 1070’s on a AX1200i.

I said I wouldn’t, not that you can’t but if you would it’s probable having some power shortage problem.

I use 3 PSU for 3000 Watt and I pull out “only” 1900W, for power efficiency reason, less cost (550$ 3 1000 W platinum PSU) more spare cables and a better scalability.

Are you sure it could cause problems? I’ve powered riser from one psu and gpus from another psu and I never had problems.

Also I do believe that risers draw extra wattage, maybe not 45W but I believe (personal experience) at least a stable extra 20W, correct me if I’m wrong.

Worst case scenario:

1) Your Antec should be 80Plus bronze certified, which means that it should be able to generate 82% conversion from AC to DC at 100% load:
1000W x 0,82 = 820W

2) Your Corsair AX1200i is 80Plus platinum certified, which means that it should be able to generate 89% conversion at 100% load:
1200W x 0,89 = 1068W.

Source: 80Plus categories (

So this is the total power you can play around with.

:arrow_up:The above calculations are most likely wrong, as it seems that the wattage rating of the PSUs are actual output. The 12V rail on the Antec is only rated for 840W, though.

If you connect the system + 5x of your MSI cards (+risers) to the Corsair, that would be a total of 850W (give or take for system power estimate).

Then you could connect these to you Antec: 2x MSI cards (300W) + 1x EVGTA (170W) + 1xZotac (250W) + 4 risers = 720W

This way you will get roughly 200W headroom on your Corsair PSU (which is good if the 100W estimate for CPU/SSD/RAM/Mobo is off) and 130W headroom on you Antec PSU. I don’t see why this won’t work. If you reduce TDP when mining (which you should do to get more efficiency), the headroom gets even bigger.

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The Antec seems to have only a 100 watt head room is that enough? One thing. I have to thank you. I always thought that you had to add in the pcie riser watts. Another thing I still have a lot to learn. I didn’t realize that you didn’t actually get 1200 watts from a 1200 watt power supply. Like everything else in this world. A piece of wood measuring a 2" x 4" isn’t 2" x 4’’ It’s 1 1/2" X 3 1/2".

Thank you. I am learning some. My house is old so I am assuming that the breakers are 15 amps. Would this be enough for one rig that I have been talking about? Next year I may add 2 -20 amp lines.

If you live in the US, you have 120V right? If so, a 15amp breaker lets you draw 120 x 15 = 1800W. However, such circuits are not designed for max power draw continuously. You got to withdraw 20% from that. So 1800W x 0,8 = 1440W. This is the wattage you can safely draw from a 15 amp circuit 24/7.

If the power requirement estimates are correct, the Corsair would require 850W / 0,89 = 955W fram the outlet. The Antec would require 720 / 0,82 = 878W from the outlet. The combined power draw would then be 1833W, which is more than a 15 amp circuit would be able to handle.

A 20 amp circuit 24/7 would give you 120V x 20A x 0,8 = 1920W (which should be enough).

EDIT: If you could shave off appr 400W from your setup, you could run everything on one 15amp circuit. Loose some of the cards and/or underclock and reduce TDP. In order to reduce power consumption with 400W total without reducing the number of GPUs, you’re looking at a TDP setting less than 70% across all GPUs.

I thought the same thing and if I got rid of the EVGA and the Zotac. The Corsair would stay the same. But the Antec would lose two cards and 2 risers. That would change it from 720 to 300 / 0,82 = 366 watts. Giving a new total of 1321 watts.

Correct. Then you’d be within the limit of your 15amp circuit. But remember, the power usage of CPU/RAM/motherboard/SSD is just an estimation. If you’re 100W off, you’d be living on the edge. But I think you’d be able to run this at stock settings. Non the less, I’d recommend that you reduce TDP before mining to increase efficiency and reduce power costs.

FYI, I have my cards (GTX 980 + 2x 1080Ti) running at 80-85% stable with a slight overclock.

I have a Kill a Watt so I will be able to check the draw. I would thought you would of be running newer cards. I have 2 - GTX 980 SC ref cards in my gaming rig. And I let them mine when I am not using it. I get about 585 sols to 640 sols for the pair. No over clocks. I just run power at 91% and Temp at 69c. Fans at 78%. I tried overclocking them and it didn’t improve so I left it alone.

The 1080Ti would be a pretty new card, though. The GTX 980 is sitting in my old desktop PC. This one is mining at core +100 @ 85% TDP. It gets around 340-350sol/s at 156W. It’s watercooled so it’s sitting at a comfortable 49C. I’m waiting for an upcoming offer at my local elctronic store to buy the rest of the 1080Ti cards for my 6 GPU rig.

Sorry I thought I saw GTX 980 ti. My eyes are getting old.

I think I made an error in my first reply, I’ve added corrective strikethroughs in the original reply.

The 1000W and 1200W of the PSU specifications seem to be referring to actual DC output. I.e. this would mean that your Corsair PSU is actually able to supply a total of 1200W, although it is able to draw more than 1200W from the outlet because of heat conversion.

So the correct onversion for your Corsair PSU would then be: Outlet Wattage x 0,89 = 1200W.

Then again, your GPUs will be powered through the 12V rail only. Antac claims that your 12V combined output is 840W, while the rest can only be output to the 3.3V and 5V rail. Corsair claims that your PSU can output the full 1200W over 12V.

I’m sorry for my misunderstanding of this, but the new calculations will give you some more headroom. It won’t have any impact on the limit that your 15A circuit can handle, though (1440W).

USA modern actually has 120 and 240 (two equal center tapped from distribution transformer) so you can get much more depending on how you run your wiring. I ran two 30 amp 240v circuits for my mining, but I haven’t even come close to hitting that capacity.

Didn’t know that. Here in Europe, 230V is mostly standard, although in my neighborhood, we also have 400V. One of the circuits in my house is 3 phase 400V/16A giving me a 11kW. That’s for charging the car, though, not mining :slight_smile:

with this website you can check how much you need and what is cheaper in the long run

Not for mining rigs.

I’ve used that site multiple times to calculate for building mining rigs. Great site. Is there something particular @chucky732 that you found didn’t work for you?