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#1 2016-12-31 04:54:09

vectro
Member
Registered: 2016-10-15
Posts: 14

Unusable Lag with 4K Nvidia eGPU on X220

I am currently trying to get an EXP GDC V8 eGPU setup working nicely with my Lenovo X220, an Nvidia 670, a 4K 60Hz monitor, and the proprietary Nvidia drivers. For those who don't know, the EXP GDC is an adapter to allow a PCIE card to be interfaced into a laptops Expresscard slot. I was able to get it to boot into xorg successfully (after specifying the PCIE port in the xorg config), and have a script handy that switches over my drivers to the nvidia suite. Also I have a modded BIOS, so I was able to force the expresscard bus to PCIE v2.0. Below are the crucial details and configs:

c@X220:~ $ uname -a
Linux X220 4.8.13-1-ARCH #1 SMP PREEMPT Fri Dec 9 07:24:34 CET 2016 x86_64 GNU/Linux

c@X220:~ $ pacman -Qs nvidia
local/lib32-nvidia-libgl 375.26-2
    NVIDIA drivers libraries symlinks (32-bit)
local/lib32-nvidia-utils 375.26-2
    NVIDIA drivers utilities (32-bit)
local/libvdpau 1.1.1-2
    Nvidia VDPAU library
local/libxnvctrl 375.26-1
    NVIDIA NV-CONTROL X extension
local/nvidia 375.26-1
    NVIDIA drivers for linux
local/nvidia-libgl 375.26-2
    NVIDIA drivers libraries symlinks
local/nvidia-settings 375.26-1
    Tool for configuring the NVIDIA graphics driver
local/nvidia-utils 375.26-2
    NVIDIA drivers utilities

xorg.conf - http://pastebin.com/tdx2MvGp
lsmod - http://pastebin.com/aub1a1xc

I'm using no window compositor, just standalone i3wm.
The problem persists even if I set the nvidia powermanager to performance mode. To be clear, the cursor moves around with zero lag, terminals scroll perfectly, and web pages exhibit mediocre performance with minor tearing (except for more intense graphical content). Unfortunately if I use any graphical applications (such as eagle, vmware, steam, or even zathura PDF viewer) I get horrible lag. I've tried all of the parameters in nvidia-settings with no luck. Any suggestions?

edit: also oddly 4K youtube video is working fine when fullscreen

Last edited by vectro (2016-12-31 04:55:41)

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#2 2017-01-09 21:30:10

LyCC
Member
Registered: 2012-09-05
Posts: 155

Re: Unusable Lag with 4K Nvidia eGPU on X220

Hello,

"Also I have a modded BIOS, so I was able to force the expresscard bus to PCIE v2.0"
without forcing it it was PCIE v1?

Also what is your monitor connected with (hdmi or display port)?

Also "zathura PDF viewer" i don't think its using any hardware acceleration (at least i couldn't find any info on that) so ...
i'm not an expert, not even close, but it sounds to me like you might have an insufficient transfer rate to the GPU??
I don't know if there is any benchmark for linux that tests the actual PCIe throughput, but if it ware me, that's where i would start.

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#3 2017-01-10 20:04:35

vectro
Member
Registered: 2016-10-15
Posts: 14

Re: Unusable Lag with 4K Nvidia eGPU on X220

Yeah I just verified and when the PCIE mode is set to auto it does default to V2, so I was mistaken.
More interestingly is the fact that on games like Portal 2, CS:GO, and Left 4 Dead I'm getting framerates over 100FPS consistently at 4K and they're all completely smooth. I have a hard time believing that my desktop activity is taking more PCIE bandwidth then 3D games. It's kind of frustrating, because gaming is the last reason I got this setup. I needed smooth 4K graphics for productivity and CAD.

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#4 2017-01-10 20:58:20

LyCC
Member
Registered: 2012-09-05
Posts: 155

Re: Unusable Lag with 4K Nvidia eGPU on X220

I'm no expert, but did you tested that card in a PC, does it run the CAD software there fluently with the 4k setup?
This way you could rule out the card it self, the drivers and the software as being a possible cause.

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