Lossless Scaling 3.0 – Dual GPU Setup Issues (RTX 3060 + GTX 1660)

[Giovarco]

Hey everyone,

I recently tried setting up Lossless Scaling 3.0 with dual GPUs, pairing my RTX 3060 12GB with an old GTX 1660 (non-Super) 6GB on a B450 Tomahawk motherboard. My goal was to use frame generation on the GTX 1660 while keeping the RTX 3060 as my main GPU.

However, the results were pretty disappointing—I lost a significant amount of FPS instead of gaining any performance. In the end, I gave up and removed the second GPU.

Confusion Around Dual GPU Setup

One of my biggest frustrations is the lack of clear guides on setting up LS 3.0 with multiple GPUs. I don't know if my motherboard is the issue or if there are specific requirements I missed. I do know that my second PCIe slot only runs at x4, but I’m unsure if that’s the bottleneck.

Has anyone successfully run LS with a dual GPU setup on a board with a similar configuration? Are there any motherboard-specific requirements I should be aware of?

Driver & Windows Settings Issues

I'm also struggling to understand what’s needed on the driver level. Should I install the Nvidia drivers normally for both GPUs? Do I need to disable certain features in Windows to make LS work correctly? Any detailed guidance on driver setup and system settings would be super helpful.

How to Determine If a Secondary GPU is Good Enough?

Before attempting this, I saw videos of people using integrated GPUs successfully as the second GPU for frame generation. So I assumed a GTX 1660 would be more than capable. But clearly, something didn’t work as expected.

Is there a way to estimate in advance whether a GPU will be suitable for LS? Are there key performance metrics (VRAM bandwidth, CUDA cores, etc.) that affect its viability as a secondary GPU?

Looking for Advice

If anyone has successfully set up LS 3.0 with dual GPUs, I’d really appreciate any guidance. Particularly:

Any BIOS or motherboard settings I need to check?

Correct driver installation process for multiple Nvidia GPUs.

Windows settings adjustments to ensure proper performance.

How to assess whether a secondary GPU is even worth using for LS.


Thanks in advance for any help! Would love to get this working properly.

[Giovarco]

Here’s a draft for youHey, I wanted to add an update based on my testing.

I tried Baldur’s Gate 3 with this setup, and I can confirm that the game was definitely using the RTX 3060 for rendering, while the GTX 1660 was handling Lossless Scaling. Task Manager clearly showed both GPUs in use as expected.

[Giovarco]

Side note: this whole story is a bit upsetting because I've read of people using GTX950 for FG only with success...

[ラリックマ]

I apologize if this is difficult to understand as I'm using machine translation.
I had a similar problem to yours, but I was recently able to fix it.

To get straight to the conclusion: I solved the issue by swapping my GPUs - putting the secondary GPU in the PCIe x16 slot 1 and the main GPU in the x4 slot 2, then outputting the display through the secondary GPU, which resulted in normal operation.

My PC configuration is: RTX 4080 as the main GPU and RTX 2060 as the secondary GPU.
When I tried using the RTX 2060 for frame generation, the frame rate not only failed to increase but actually decreased significantly at WQHD and 4K resolutions. Looking at GPU utilization, the 4080 was normal, but the 2060 was reaching 100% utilization.

At first, I thought it was due to the RTX 2060's insufficient performance, but I noticed the power consumption was low despite the 100% utilization.
Upon closer examination, I found that VRAM and "3D" was barely being used, while "Bus Interface" and "Copy" were at 100%.

It seems the x4 lanes in slot 2 didn't provide enough bandwidth. Additionally, displaying the monitor through the secondary GPU reduced the "Copy" utilization.

Of course, I was concerned that putting the main GPU in the x4 slot 2 would reduce the base frame rate, but the decrease was about 10%.

I'm not sure if simply rearranging your GPUs will fix your issue, but I hope this solution works for you as well.

[ラリックマ]

Additional note:
I had been running at 4K 120fps with HDR enabled, but when I turned HDR off, the main and sec GPUs usage and power consumption became almost nomal, so frame rate without dropping was achieved
Although turning off HDR does reduce bandwidth, I think it is very strange that it would make such a significant difference.
It's a bit disappointing, but I'll play games with HDR turned off from now on.

[andraspribelszki]

For me on 2x PCIe 3.0 x8, the copy-back operation (when the render GPU is also the display GPU, and the frames being copied between the two GPUs two times) only works properly when I enable the reBar funcion via nV profile inspector. With reBar off I have to use the secondary GPU (the one busy with LSFG) as display output because of the massive performace drop (useless, basically). If you change your setup to work like this, keep in mind that in the future you'll have to re-enable reBar* after each driver update!

*Make sure that i'ts also enabled in the BIOS settings.

[DENZ]

Originally posted by ラリックマ:

I apologize if this is difficult to understand as I'm using machine translation.
I had a similar problem to yours, but I was recently able to fix it.

To get straight to the conclusion: I solved the issue by swapping my GPUs - putting the secondary GPU in the PCIe x16 slot 1 and the main GPU in the x4 slot 2, then outputting the display through the secondary GPU, which resulted in normal operation.

My PC configuration is: RTX 4080 as the main GPU and RTX 2060 as the secondary GPU.
When I tried using the RTX 2060 for frame generation, the frame rate not only failed to increase but actually decreased significantly at WQHD and 4K resolutions. Looking at GPU utilization, the 4080 was normal, but the 2060 was reaching 100% utilization.

At first, I thought it was due to the RTX 2060's insufficient performance, but I noticed the power consumption was low despite the 100% utilization.
Upon closer examination, I found that VRAM and "3D" was barely being used, while "Bus Interface" and "Copy" were at 100%.

It seems the x4 lanes in slot 2 didn't provide enough bandwidth. Additionally, displaying the monitor through the secondary GPU reduced the "Copy" utilization.

Of course, I was concerned that putting the main GPU in the x4 slot 2 would reduce the base frame rate, but the decrease was about 10%.

I'm not sure if simply rearranging your GPUs will fix your issue, but I hope this solution works for you as well.

What motherboard do you have?

[Slahous]

Plug the monitor into the gpu that is doing the scaling. Works well on my integrated graphics card with 0 fps drop.

[Raigavin]

RTX 3060 Ti (Main GPU)
RX 6400 (PCI-E 3.0 x4).

Display 1 - RTX 3060 Ti
Display 2 - RTX 3060 Ti
Display 1 (again) - RX 6400
Note: Monitors are 1080p, 120Hz

Displays (DP and HDMI) connected to RTX 3060 Ti are on 2880x1620 (via DLDSR)

Display 1 (HDMI) connected to RX 6400 is on 3072x1728 (via VSR)

When I want LS FG, I switch to use Display 1 using RX 6400 and run game on Display 2 using RTX 3060 Ti.

I use game render at 2880x1620 with DLSS or other upscaling on RTX 3060 Ti and the LS FGx3 (with LS1 Upscale sharpness 1) on RX 6400 output. From 40FPS to 120Hz FG.

Works fine for me with my setup and configuration or resolutions
- Kingdom Come Deliverance 2 (DLSS)
- Cyberpunk (Path Tracing) (DLSS Perf) 25FPS to FGx2 for 50Hz or even FGx3
- Expedition 33 (DLSS Quality) 20-40FPS to FGx3 60-120Hz
All of the above at game render of 2880x1620

Note: the DLDSR Upscale doesn't have any effect on the FG output, except running the game at that resolution. Because the final image output of FG is via AMD GPU in VSR. I mainly use it to subtlely increase my image quality when using Displays on RTX GPU. So you can omit that part. I mentioned them for reference if people would ask "Is it working multiple bells and whistles?".

Note 2: Should run fine on Single Monitor too. But again, I mentioned my weird multiple display settings incase someone asks about "other combinations".