Thinkpads Forum

I was searching for answers, trying to find the best info abt a T420 connected to an eGPU. There are ups and downs but somewhere the mobility comes first.

There are as far I can see two major solutions, one uses the ExpressCard, second the mPCI-e slot. Either I cannot search or there is no real compare between efficiency of both connections. I would like to use as base the EXP GDC Beast solution. It offers two models, mPCI-e and Express. Lets take as an example the nVidia GTX760, which uses a PCI-e 3.0 bus and uses x16 "lenght"/"lanes". As far I found, both connections to T420 will act as PCI-e 2.0, a small disadvantage. But will it be x16? Or just a x1? How much in % will the GPU loose compared to a desktop PC configuration?

Thank you in advance for helping me out, I would also like to hear from Tx20 eGPU users about their experience.

But will it be x16? Or just a x1?

The Expresscard is x1. mPCIe is also x1. It's possible to combine the two to make an x2 connection, provided that:
1. your eGPU dock supports multiple lanes.
2. you can run the cable from the mPCIe slot to the eGPU dock.

As for the performance loss, I do not know because I've never done an eGPU setup before.

I was just pondering this as well yesterday simce the t420 series won't support UHD resolutions. i'm debating on whether it would be worth it or not. Definately seems more like a hack and not a plug and play solution ("delay turning on the egpu until after POST but before booting windows"

plympton wrote:I was just pondering this as well yesterday simce the t420 series won't support UHD resolutions. i'm debating on whether it would be worth it or not. Definately seems more like a hack and not a plug and play solution ("delay turning on the egpu until after POST but before booting windows"

The eGPU will be PCIe 2.0 x1

You will have a performance loss of around 30%.

QWERTY Andreas wrote: The eGPU will be PCIe 2.0 x1

You will have a performance loss of around 30%.

That's what I was looking for. Will update with the results. Hope for playable results.

I have a X220t with a eGPU setup (ExpressCard). Running a GTX560SE, mostly on internal LCD using optimus compression. 3Dmark 11 of 3299 with a Core i5-2520m.

Setup:
If your T420 have only Intel Graphics, setup will be relatively straight forward

Experience:
eGPU can be unplug while the system is running using the "Safetly remove hardware" function. The only catch is eGPU must be plug in and active during system start.

Another point to note is that on an external display, higher performance can be achieved.

I have T430 with eGPU (actually - have had, because I had to leave it in Poland when I was moving to China). It can run only in x1, and the performance loss depends on specific games (or rather their engines), you may want to check out my topic about it, it might give you an idea about the setup (link in my signature).

@kony your setup was an inspiration to me, i'm actually looking for a matx/itx case to put psu and graphics inside. Maybe it can include some wd red's for storage. Sick of attaching a 2TB external. As a goal I will try to play Witcher 3 in FHD on medium on an external monitor.

@bluefruit external display is ready, btw it's a Lenovo L220 16:10 FHD, have it for almost 7 years and love it.