PSU for two 3090s?

[Dari69]

I have a 3090 fe and 2070 that are both mining those are using their under clocked wattage. I recently bought 1000 w EVGA supernova P5 platinum power supply and it has enough power for me to max out the 3090 and the CPU while also mining on the 2070 but I’m adding a second 3090 for mining and was wondering if I would need a 1600 W power supply or if I could keep my thousand watt power supply? The sustained load would be around 720 watts mining but for power spikes and all I think I would need a higher watt power supply? Also if I were to game on one of the cards while mining on the two other the load will go up to 950 then I definitely think I will need a higher PSU but the question is which one 1200 1300 or 1600 watt. I was thinking EVGA Supernova 1600 G+, 80+ Gold 1600W. But I don’t know if that is overkill I definitely don’t want to cheap out on a power supply but I don’t want to buy something that I don’t need like buying an 850 PSU for a system that uses 400 W. Also is gold rating OK on wattage that high? (I wanna be able to pull max power from at least one 3090 and the rest of the system (cpu ram ect) except the other GPUs they are mining at <85 power limit so I’m thinking 1600 watt? But I'm in a dilemma.  (System i 711 700 K 5.2 GHz all core overclock 32 gigs of 4000 MHz ram 1000 watt EVGA P5  supernova platinum 2x 3090 fe msi ventus 2070 240mm aio 2 140mm case fans 1 sata wd blue ssd 1 sata 2.5 inch hdd 1 sn750 nvme. MB: GIGABYTE Z590 AORUS ELITE.) obviously I don’t think that there is any real question here because I’m getting the evga supernova g+ 1600 w 80+gold for $349 on Amazon is it a good power supply? Is that a good deal?

[BiotechBen]

Its better to overspec than underspec. General practice is to take full load wattage +50%, but with dual 3090s I would say that the 1600W is probably going to be mandatory unless you wanna go jank-tastic and use the 1000W for the main system and a 1300W with jumpers for the 3090s(NOT RECOMMENDING THIS, ALL ASSUMED RISK IS THAT OF THE OWNER)

[IkeaGnome]

Why not just run dual PSU instead of buying another power supply?

[Dari69]

12 minutes ago, IkeaGnome said:

Why not just run dual PSU instead of buying another power supply?

I thought about doing that but people said it wouldn’t work I don’t know how I’ve seen many set ups do that people said it would be different  voltages would interfere but I don’t know how im plug ing the entire GPU all of the PCI pins into the same PSU I’m not plugged in like half the CPU into it and then etc. 

[Dari69]

28 minutes ago, BiotechBen said:

Its better to overspec than underspec. General practice is to take full load wattage +50%, but with dual 3090s I would say that the 1600W is probably going to be mandatory unless you wanna go jank-tastic and use the 1000W for the main system and a 1300W with jumpers for the 3090s(NOT RECOMMENDING THIS, ALL ASSUMED RISK IS THAT OF THE OWNER)

Yeah especially on the PSU do you know if this is a good one EVGA Supernova 1600 G+, 80+ Gold 1600W

[IkeaGnome]

Just now, Dari69 said:

I thought about doing that but people said it wouldn’t work I don’t know how I’ve seen many set ups do that people send it to voltages would interfere but I don’t know house unplugging the entire GPU all of the PCI pins into the same PSU I’m not plugged in like half the CPU into it and then etc. 

Im running dual with 4 GPS. Rm1000x does motherboard, CPU, 1080 and 2070. 

750x does 1080 and 1070. 

The only tricky part is to get them to turn on at the same time. 

You can either get a cheap adapter for this. It'll look like a 24 pin extension cable, but it'll have another 24 pin connector on it with 2 wires is all. This will tell the second PSU to turn on. 

While I was waiting on an adapter I used a piece of wire to short the power on pins in the 24 pin and then just used the PSU switch on that power supply when I also pushed the on button on the case. It took some timing, but worked well.

Then I got smart and took some spare Ethernet, stripped both ends back, and then stripped some copper out. Jammed the copper in the back of both pins on both 24 pin connectors and used that Ethernet cable as the adapter. 

Adapter I use

Spoiler

With shorting the pins, 16 is the important one. Most do 16 and 17. This completes the on circuit just like the motherboard or case button would do. As long as you do 16 and any of the grounds, you're fine.

[Dari69]

14 minutes ago, IkeaGnome said:

Im running dual with 4 GPS. Rm1000x does motherboard, CPU, 1080 and 2070. 

750x does 1080 and 1070. 

The only tricky part is to get them to turn on at the same time. 

You can either get a cheap adapter for this. It'll look like a 24 pin extension cable, but it'll have another 24 pin connector on it with 2 wires is all. This will tell the second PSU to turn on. 

While I was waiting on an adapter I used a piece of wire to short the power on pins in the 24 pin and then just used the PSU switch on that power supply when I also pushed the on button on the case. It took some timing, but worked well.

Then I got smart and took some spare Ethernet, stripped both ends back, and then stripped some copper out. Jammed the copper in the back of both pins on both 24 pin connectors and used that Ethernet cable as the adapter. 

Adapter I use

  Reveal hidden contents

With shorting the pins, 16 is the important one. Most do 16 and 17. This completes the on circuit just like the motherboard or case button would do. As long as you do 16 and any of the grounds, you're fine.

OK what do you mean by the grounds though? I knew about the shorting but not about the ground. Is it to trick the power supply into thinking and that it’s plugged in or something that wouldn’t make any sense I don’t know of anything could you please explain.

[IkeaGnome]

2 minutes ago, Dari69 said:

knew about the shorting but not about the ground. Is it to trick the power supply into thinking and that it’s plugged in or something that wouldn’t make any sense I don’t know of anything could you please explain.

You're correct.

In the spoiler, see how pins 3,5,15,17,18,19 and 24 are ground? When pin 16 and ground are connected, usually by your motherboard, that's the motherboard completing the circuit with a relay to tell the power supply to turn on. If you short that, or use the adapter, you're just using something to complete the circuit. 

 

If you want to try it without having GPUs hooked up. Most people just use a paperclip. Unplug your psu from the wall, or use your old PSU. Unbend a paperclip and bend it to connect pins 16 and 17. Push it into the two pins inside the connector. These are very low voltage, low amperage. You can touch them and not feel even static electricity. With these pins shorted, make sure the switch on the back of the PSU are off. Plug into the wall. Turn on. Your psu will turn on like normal. Use the switch on the back to turn it off.

[Dari69]

15 minutes ago, IkeaGnome said:

You're correct.

In the spoiler, see how pins 3,5,15,17,18,19 and 24 are ground? When pin 16 and ground are connected, usually by your motherboard, that's the motherboard completing the circuit with a relay to tell the power supply to turn on. If you short that, or use the adapter, you're just using something to complete the circuit. 

 

If you want to try it without having GPUs hooked up. Most people just use a paperclip. Unplug your psu from the wall, or use your old PSU. Unbend a paperclip and bend it to connect pins 16 and 17. Push it into the two pins inside the connector. These are very low voltage, low amperage. You can touch them and not feel even static electricity. With these pins shorted, make sure the switch on the back of the PSU are off. Plug into the wall. Turn on. Your psu will turn on like normal. Use the switch on the back to turn it off.

OK I’ll use my spare psu The golden rule is to never have to power supplies going into the same device drawing power like one of the eight pin connectors on a 3090 have a different PSU than the other eight pin connector.

[IkeaGnome]

Just now, Dari69 said:

OK I’ll use my spare psu The golden rule is to never have to power supplies going into the same device drawing power like one of the eight pin connectors on a 3090 have a different PSU than the other eight pin connector.

Correct. All power for the 3090 from one PSU or the other. 

You'll have to play with it a bit to get the timing right on turning the second PSU on. It's same time or just before you push the power button for the motherboard. 

[GreenArrangements]

Wouldn't 1300w be enough for dual 3090s alone?

Full power draw of this system was around 1000w~, 1300w would be enough. But I see the author has another 2070, so 1600w indeed should be needed there.

 

[Guest]

5 hours ago, Dari69 said:

I thought about doing that but people said it wouldn’t work

You're talking to the wrong people.  

[Dari69]

On 12/13/2021 at 9:30 PM, jonnyGURU said:

You're talking to the wrong people.  

lmao ur right.

[Dari69]

On 12/13/2021 at 8:05 PM, GreenArrangements said:

Wouldn't 1300w be enough for dual 3090s alone?

Full power draw of this system was around 1000w~, 1300w would be enough. But I see the author has another 2070, so 1600w indeed should be needed there.

 

yes between sustained load it may be around 1000-1150, but just between the peak pull of 2 3090 is 900w maybe more so add a 250 w 2070 and a 250w cpu. And 1600w is the solution thanks.

[Dari69]

Thank you guys I put one 3090 on a 600w 80+ platinum psu i had laying around with nothing else on it and it has been running fine stress tested it for 10hr @ 400+w to make sure.