[SOLVED] 2 x RTX GPU's on 750 PSU?

[Wedzayblooz]

Hi, I currently have 2 Ryzen 7 3700x PC's. One has a RTX 3070 in it, the other a RTX 2070. The PC with the 2070 does nothing but mine all day and the PC with the 3070 in it is currently used for gaming/personal use and mining the rest of the time. I would like to know if it is possible to put both the 3070 and 2070 into the same case and whether this would be within the PSU's power limits?

Motherboard is MSI Gaming Plus X570 (has 2 PCIE slots)
PSU is Corsair RM750
2 x 8bg ram
1 x SSD
1 x NVME SSD
Ryzen 7 3700x stock
Artic E-Sports Duo CPU cooler
2 x 140 fans
3 x 120 fans

Pushing it further I would like to swap the 2070 out for another 3070 (if I can get hold of one) so again, would the PSU be sufficient? I wouldn't mine when gaming so not too concerned about temps as only one card would be on the go when gaming and the case is pretty well cooled. Both cards have slight undervolts.

I know it would be pushing the PSU to its limits but I'm reluctant to go out and buy another PSU if I don't know how long mining is profitable for and I'm only mining in the first place to offset the cost of paying over the odds for the 3070!

Using Power Supply Calculator - PSU Calculator | OuterVision it calculates my load wattage as 602 W with both a 3070 and 2070 at stock voltages - is this within safe parameters and what exactly happens if load wattage exceeds 750 W?

Load Wattage:602 W
Recommended UPS rating:1100 VA
Recommended PSU Wattage:652 W

Amperage (combined)​ ​ � +3.3V​ +5V​ +12V​ 13.4 A​ 8.7 A​ 47.0 A​ 88 W​ 564 W​

Lastly, is there any drawback to taking up 2 PCIE ports/lanes on the motherboard i.e would having 2 GPU's installed negatively effect the performance of one of the cards, even if the other was not in use at the time?

 

[Bassman999]

The sweet spot for ETH mining according to the internet is 160 watts
3700x is a 95w tdp chip that uses way less mining. I think it will be totally fine since you have a good PSU
I think you will be at 500 watts or less mining with both

 

[carocuore]

what exactly happens if load wattage exceeds 750 W?

PSU shuts off

It's enough for both cards but you could undervolt the 2070 so less power is wasted

 

[Bassman999]

PSU shuts off

It's enough for both cards but you could undervolt the 2070 so less power is wasted

Undervolting is good since ETH mining doesnt need a high core frequency only memory used mainly

 

[Wedzayblooz]

Thanks for the replies. Both GPU cards are currently undervolted anyway as they seem more stable this way for pretty much everything. When they mine they are underclocked on core clocks with memory pushed as high as they will go. Was hoping this would reduce their combined wattage as they will only both be on at same time if I am mining but don't really understand voltage etc so wanted to check before I blew something up. All other scenarios I think I will play it safe and just run the one GPU.

I'm going to sell the other pc, cpu etc and recoup some money back. Id like to keep the better performing ryzen 7 3700x cpu if there is a difference between em, even if this means swapping em over before I sell. Is there a fair way to bench/test 2 of same CPU's in different motherboards?

 

[Wedzayblooz]

Oh yeh and does having 2 gpu's on the same motherboard affect gaming performance when only using one GPU? Is bandwidth reduced or something?

 

[Bassman999]

Thanks for the replies. Both GPU cards are currently undervolted anyway as they seem more stable this way for pretty much everything. When they mine they are underclocked on core clocks with memory pushed as high as they will go. Was hoping this would reduce their combined wattage as they will only both be on at same time if I am mining but don't really understand voltage etc so wanted to check before I blew something up. All other scenarios I think I will play it safe and just run the one GPU.

I'm going to sell the other pc, cpu etc and recoup some money back. Id like to keep the better performing ryzen 7 3700x cpu if there is a difference between em, even if this means swapping em over before I sell. Is there a fair way to bench/test 2 of same CPU's in different motherboards?

There are other factors in a benchmark like ram power stage on MB etc that will affect CPU score. I dont think any way to tell for sure except to swap them on the same board for testing.
AS far as gaming with the 2nd card not connected IDK. I would guess if its not connected to a monitor is should not make a difference but just guessing.

 

[carocuore]

Oh yeh and does having 2 gpu's on the same motherboard affect gaming performance when only using one GPU? Is bandwidth reduced or something?

Short answer: no, not even when you're using multiple cards but only gaming in ONE.

If SLI/Xfire is enabled both cards will try to run at 16X if the mobo allows it, otherwise both will run at 8X, but if both cards are present and SLI is disabled then 1 card (master) will run at 16X and the other (slave) at 8/4X but only if BOTH slots are 16X, otherwise the slave card will run at 4X, this isn't a big deal when you're mining.
CPU usually has enough lanes to run a card at 16X and another at 8/4X or 2 more at 4X each.

I'm running 3 cards, the master card that's for gaming and video output always needs to be located at the first slot and the slaves below it, in my case it's a 16+4+4 config. There's absolutely no problem in something like this but you'll need enough RAM to be able to run a game and the mining software at the same time, in your case 16GB should be plenty to do both unless you run a game that devours 10+ GB.

Pros: can game and mine at the same time.
Cons: noise, room temperature.

 

[Wedzayblooz]

Thank you for going into such detail. I appreciate it. Think I'm going to go ahead and sell my other pc and try the 2 gpu set up.