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

[chuck732]

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.

[Vann]

You need to reduce the power limit on the cards to reduce the power consumption. Even then I don't think it's possible to run six 1070's on a single 1000W PSU. I have a Zotac AMP! Exteme GTX 1070 mining ZEC and it uses ~185 W at 75% power limit.

[chuck732]

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?

[Vann]

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?

With two 1000 W PSU you should be able to run 9 1070 without a problem if you adjust the power limit on the cards. Where are you getting your power consumption values from? For Nvidia cards, the power consumption shown in software tools includes the risers. For AMD cards, you need to add 40-50 W for the riser. You need to get a power meter so you can measure the actual power draw from the wall and divide the power across both PSU's evenly to keep them at an efficient power level.

[chuck732]

I haven't finish putting it together.

Where are you getting your power consumption values

I'm getting them from the makers of the cards. Like MSI specs. They say they use 150 watts. The power for the risers I got from a Youtube channel Bits Be Trippin'. He said the riser use 40 to 50 watts. Right now I am waiting on another MSI GTX 1070 Gaming X card. So I was planning to finish rig today with just the 6 - MSI's and 1 - EVGA GTX 1070 SC. Leave the Zotac out and when the other MSI gets here add it in to the rig. For now I think I have enough power 7 cards and 7 risers. Was told not to run 6 1070's on the AX1200i, that's why I post how I was going to change it.

[shibob]

I usually choose PSU based on this calculation: Desired Power = (total GPUs_Power)/0.7. The rest 15% should be for other peripherals.

For example, my rig includes 6 cards 1070, each card draws 150W, 6 cards = 150W*6 = 900W, so PSU should be around: 900W/0.7 = 1285W => 1250W PSU is good enough.

[chuck732]

What is?

/0.7

[noloco]

What is?

/0.7

You need to take into account PSU efficiency, usually it is between 80 and 90 per cent, some energy from input will be wasted as heat during conversion from ac to dc.

To take this into account you can multiply your estimated power requirements by 1.2 or divide by 0.8 depending on your safety margin.

[chuck732]

Thank you.

What is?

/0.7

You need to take into account PSU efficiency, usually it is between 80 and 90 per cent, some energy from input will be wasted as heat during conversion from ac to dc.

To take this into account you can multiply your estimated power requirements by 1.2 or divide by 0.8 depending on your safety margin.