When I purchased T430 I instantly installed Linux Mint on it and used it ever since. Which is why it was the first operating system I tried to use my eGPU in. Nvidia doesn't make Optimus technology available on GNU/Linux systems, however, there's open-source Bumblebee which serves the same purpose. I followed the instructions for Ubuntu 13.10 to install Bumblebee and executed a command:
sudo apt-get install bumblebee bumblebee-nvidia primus linux-headers-generic primus-libs-ia32
Having open-source drivers Nouveau already installed, I proceeded to test a few games. Unfortunately, the performance in all the games was extremely disappointing, regardless of graphic settings and how demanding the games were. Kerbal Space Program, Left 4 Dead 2 and Depths of Peril all were displayed with only 8-10 frames per second, while Depths of Peril, being a low-demanding game, was running fine on maximum settings on Intel HD 4000. Afterwards I installed the newest Nvidia's linux drivers (340), but there was only a slight improvement of two more frames per second. Then I tried older 331 drivers and when I hadn't seen improvement, I removed all the drivers and libraries and repeated everything to no avail.
Because I couldn't use my eGPU on Linux Mint, I installed Windows 7 and updated it. Afterwards I installed Nvidia's 347 drivers and tested some games, but this time I had another issue - I had high frame rates but every few seconds the image would freeze for a second. The issue was present in all the games I have tried: Divinity Original Sin, Alien Isolation, Left 4 Dead 2, and so on. I tried all the available settings and nothing would help. Finally, in Killing Floor game and Valley benchmark I noticed the issue is restricted to DirectX, as in OpenGL I have a stable and satisfying performance. In the Valley I had 40 FPS with drops to 2 FPS in DirectX on Ultra details, while in OpenGL I had stable 30-35 FPS. It was a bit bewildering, but that meant the problem clearly pertains to the software and not the hardware. I installed the 340 drivers and restored the default settings in Nvidia Control Panel, then tried running Valley benchmark again - this time everything worked as it should. I had stable ~35 FPS on Ultra settings with no AA and 1600x900 resolution. Then I tested games and they were also running with high performance. A few days later I tested performance using various versions of the Nvidia's driver and this is what I found out: The best drivers for GTX 560 TI are 331. 340 gives a few FPS less than 331 (in Divinity Original Sin and Fallout New Vegas), 347 there's an issue of freezing every few seconds, and 314 works similarly to linux drivers - performance is extremely low and games run in about 10 FPS.
I am very happy with this setup as I am able to play modern games in maximum details on my T430. With eGPU it's not really a mobile hardware, but I play games only in my room anyway, when I need to take my laptop with me somewhere else I just disconnect the external GPU and use HD 4000. After all, outside I only need the laptop for simple tasks such as writing. It's just a shame Nvidia's drivers are so useless for Linux, but to be honest, all GPU drivers are disappointing in Linux. Hence why for games I have to dual boot.
