Dual 2070S on B450 Tomahalk?

[ldmartin]

My 3D rendering program of choice, Keyshot, has recently added support for GPU rendering with Ray Tracing on Nvidia cards. I'm concerned about memory capacity because I can easily fill up 10GB+ with assets and materials when rendering on my CPU. Unfortunately, you can't pool VRAM with Keyshot yet, but apparently that function is in the works. I also game on a 34" 1440p monitor and will be using the GPU to power my Oculus Quest through link.

 

I'm planning on upgrading to a 2070 SUPER soon, with the intention of adding another 2070S with NVlink when support for pooling VRAM is added, giving me 16GB total. I'm aware that the B450 Tomahawk only has 1 PCIe 3.0 x16, with an additional PCIe 2.0 x16. And the 2700X has 16 lanes for GPUs. I'm struggling to find answers as SLI in gaming becomes less popular.

 

Am I going to run into problems (PCIe, power handling, bottlenecks etc.) if I add in second card on my B450 Tomahawk with my 2700X?

 

Thanks

[GoldenLag]

PCIe layout doesnt allow for SLI afaik. as those lanes in the bottom slot are from the chipset. 

 

it does do dualcard configurations tho. 

[Chiyawa]

You may need to change your motherboard to X470/X570, and get something that has two PCIe slots for graphic (and they only run x8 lanes if both slots are occupied).

[ldmartin]

@GoldenLag @Chiyawa thanks. Keyshot can leverage multiple GPUs without Nvlink SLI but I think upgrading to a more capable mobo sounds about right.

[GoldenLag]

2 minutes ago, Chiyawa said:

You may need to change your motherboard to X470/X570, and get something that has two PCIe slots for graphic (and they only run x8 lanes if both slots are occupied).

well you only need to have 2 16x slots running at 8x CPU lanes each. 

 

that is the actual issue. 

[Chiyawa]

1 minute ago, GoldenLag said:

well you only need to have 2 16x slots running at 8x CPU lanes each. 

 

that is the actual issue. 

Indeed, but B450 chipset doesn't allow the CPU to split its PCIe lanes. X470 has that capability, and you can find many of the X470 mobo supports dual GPU and capable of SLi or CrossFire. So X470 board are ideal for dual GPU setup.

 

Also, do note that PCIe from the chipset supports PCIe Gen2 only. It'll be way slower if running a GPU card.

[1van]

5 hours ago, GoldenLag said:

well you only need to have 2 16x slots running at 8x CPU lanes each. 

 

that is the actual issue. 

It depends. His application may or may not be limited by the PCIe throughput.

@ldmartinI'd test it with a single card, changing the PCIe speed in UEFI (or putting a card in the PCIe 2.0 slot), and measuring if it would affect performance in your app. It shouldn't be that hard.

 

UPD. Just noticed that you don't have even a single 2070S yet. What card do you have?

Edited November 25, 2019 by 1van

[GoldenLag]

5 minutes ago, 1van said:

His application may or may not be limited by the PCIe throughput.

dont think SLI works on chipsetlanes. thats the actual issue. 

[1van]

@GoldenLagHe has confirmed that the software doesn't require SLI. I don't know this particular software, but I know this to be true for other similar applications. It can even run AMD and nVidia GPUs at the same time.

[GoldenLag]

1 minute ago, 1van said:

@GoldenLagHe has confirmed that the software doesn't require SLI. I don't know this particular software, but I know this to be true for other similar applications. It can even run AMD and nVidia GPUs at the same time.

OP is talking about shared Vram. which would require SLI