2017 15" Alienware 15 R3 (GTX1070) [7th,4C,H] + GTX 1080 Ti @ 32Gbps-TB3 (ASUS XG Station Pro) + Win10 1803 [itsage] // TB3 vs Alienware Graphics Amplifier  

@itsage Looking at the last three results, seems like bandwidth limits given how a laptop 1070 is doing better than a 1080 Ti over TB3? If not, what do you think accounts for the difference for these two GPUs in those games? Could you also add tests for 2080 Ti over TB3 to the results?

@mac_editor I think 22Gbps bandwidth might not be the issue but rather the Thunderbolt 3 controller speed. Certain games make it harder for the end-to-end encoding and decoding by the TB3 controllers. I ran the RTX 2080 Ti and Radeon VII recently to compare dGPU vs eGPU. You'd see a very similar limits in games such as Forza Horizon 4, Assassin Creed Odyssey, and Ghost Recon.

@itsage in my comparison between GTX 1080 Ti and RTX 2080 Ti, the RTX2080Ti could hardly beat the GTX1080Ti, only by an average of 7 FPS.

This is completely different to your results, where the RTX 2080 Ti wins handily.
How can this be explained? Can this be the difference because of brand and type of the card?

Ah, It's not TB3, it's AGA, this explains something, of course.

FYI:

@oliverb The Alienware Graphics Amplifier is faster than Thunderbolt 3 connection. Here's a direct comparison using an RTX 2080 in the Razer Core and AGA.

@itsage: Great table as always.

Question: Did you merge my two posts before or is this done automatically?

I merged them manually. We had requested the forum software developer for auto-merge feature but it's not possible yet.

@itsage thank you for the insight. Okay, so the TB3 encode/decode is the bottleneck for those games. But what influences this encode/decode? In the 3 games in question, why is the encode/decode process slower vs. other games? If we can understand what properties exactly affect performance (such as specific game settings, textures, etc), it would be an important step forward in understanding TB and it’s limits.

@itsage, it's interesting how same GPUs can differ from brand to brand. I get easily up to 10% better values with my GTX1080Ti compared to yours.

Such differences make it hard to compare correctly.

For example, compared with your GTX 1080 Ti, a RTX 2080 Ti may be 20% better, which is a good improvement, but it's only 10% better compared to mine, which is a bad value.

Other example is the comparison with Radeon VII: My GTX 1080 Ti was 10% better than the Radeon VII in average, but of course this would be different compared with another GTX 1080 Ti which is 10% worse...

@itsage, you should, no, must, test new Vulkan Games like Doom or Wolfenstein 2. The performance of Vulkan is incredible. I would be very interesting how a RTX2080Ti on AGA performs.

See this Vulkan Thread.