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  1. #1
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    Join Date
    May 2017

    Exclamation Thunderbolt 3 Bandwidth

    Hello everyone!

    Thunderbolt 3 eGPU setups have many performance issues that should be addressed to appropriate manufacturers.

    1. H2D speed - FIXED
    Low Host to Device speeds (~1100mb\s) shown by CUDA-Z utility affected performance in bandwidth-use-heavy games, but, fortunately, this issue was fixed by almost all egpu enclosure developers including ASUS, Akitio, etc.

    2. Intel firmware throttles bandwidth from 32GB to 22GB.
    Please check this picture: How it works

    According to forums (eGPU community) TB3 in reality provides 32gb bandwidth (8gb reserved for encoding\decoding etc), but for egpu only 22GB are available (as data bandwidth).
    It seems like 32Gb are throttled on software level into 22gb (10GB are reserved for display port and\or usb-c bandwidth). Is it possible to somehow ( by fw update?) unleash full bandwidth for egpu enclosures?
    Maybe fps drops are related to controller optimizations (not bandwidth issue)? Or there should be done some modifications to Nvidia drivers? There are some eGPU drivers for Quadro (do they include some optimizations?)
    I've contacted Intel - they told that only companies (who provide eGPU enclosures) like ASUS should modify thunderbolt firmware to fix anything related to firmware.

    3. Thunderbolt 3 decoding\encoding optimizations. Some games are bottlenecked not only by H2D speed.

    Observations and results:

    I'm using ASUS UX501VW laptop (4-lane tb3) with Alpine Ridge (1575) Thunderbolt 3 controller (FW version is 25 and latest eGPU oriented BIOS update) and eGPU enclosure Akitio Node with Strix 1080Ti onboard.
    Should scene (not every heavy scene though) in game be little bit more complex - 100+ fps are falling into ~48 fps. It looks like performance is bottle-necked by something. It worth noting that same card (same even for older gpu's) doesn't have issues with such desktop. (I'm aware of obvious drop on high (150+) drop).

    Assassin’s Creed Unity gives me stable 60 fps, but drops to 46 fps in “assassin’s base” building. Assassin’s Creed 4 Black Flag drops to 45 fps in jungle if environment quality is set to high or ultra (doesn’t matter). If environment setting set to medium or low – less detailed trees and stable 60 fps throughout all game. I know Ubisoft optimization problems, but on 1080 ti? What about Blizzard’s WoW game? What about GTA 5? Even GTA 5 has fps spikes on eGPU. There is definitively something wrong with performance of eGPU's through Thunderbolt 3.

    World of WarCraft:

    Game shows EXACTLY same FPS value (46-48) on heavy scenes with ANY resolution. Desktop, obviously, has no such issues.

    800×600 (used almost lowest possible):
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    2560×1440 (2K):
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    Last edited by Jaye95; 08-19-2017 at 04:32 AM.

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