External graphics card experiment: Part 1

External graphics card experiment: Part 1

I always wanted to have a small light portable computer on the go and when I get home to use a docking station and get the full desktop experience. Following other people examples on the internet I have made this cheap solution with and external graphics card in the docking station (eGPU) that can be used with an external monitor or accelerate the internal screen of the laptop.

Parts

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That is 415 USD for the setup without the laptop and graphics card and 690 USD with the graphics card included. Notice all prices are in USD but I live in Denmark so prices are higher than the states.

Setup

My laptop is connected via thunderbolt to the Sonnet Echo Thunderbolt to ExpressCard adapter which is connected to the PCI-E 1x ExpressCard adapter. I connect the graphics card to this PCI-E 1x port, the power supply unit and case.

Final eGPU setup
Closeup of GPU inside the case

The setup is configured to start when the laptop start or wakes from sleep and turns off when the computer turns off. I have installed windows 7 64 bit. I have not used any bootloaders, memory reallocation or third-party tools like described here. Maybe it is because I don’t use MacBook in combination with bootcamp. My laptop does not contain a discrete graphics card which might have helped me avoid PCI memory allocation problems. When I plugin the cable it detects my graphic card and I install the drivers.

Performance

There are two ways of using the setup, one is to display the content on an external monitor connected to the graphic card. Another is to accelerate the laptops internal monitor, I give you performance measurements for both:

3dMark 6

  • 21028 with NVIDIA GeForce GTX 760(1x) and Intel Core i7-3520M (external monitor
  • 18829 with NVIDIA GeForce GTX 760(1x) and Intel Core i7-3520M   (internal laptop screen)
  • 6678 with Intel HD Graphics 4000 Mobile(1x) and Intel Core i7-3520M (internal laptop screen)

Looking at the first part of the test I saw these framerates:

  • GeForce GTX 760 (external monitor) 160 fps
  • GeForce GTX 760 (internal laptop monitor) 100 fps
  • Intel HD Graphics 4000 Mobile (internal laptop monitor) 30 fps

3dMark11

Laptop only, internal laptop screen
External monitor, external graphics card

I did not take a screenshot of the test using the internal laptop screen and the external graphics card, but the score was 4400.

Scaling

Using an ExpressCard adapter halves the bandwidth of thunderbolt 1, so the effective bandwidth is PCI-E 2.0 x1. This does slow down the graphics performance, but not as much as you might think:

http://www.techpowerup.com/reviews/Intel/Ivy_Bridge_PCI-Express_Scaling/1.html

Using a laptop with the new thunderbolt 2 port and a setup that support this thunderbolt port, like enclosures from Sonnet or Magma, would have a bandwidth of PCI-E 2.0 x4, four times as much, but not four times the performance. See my post about my thunderbolt 2 setup here.

Conclusion

I have succeeded in building a setup that is close to giving my the full desktop experience, with some performance limitations. Why not just buy a desktop pc on the side? Well I still only want a single computer, not two, even if the performance is reduced. Next project however is getting a laptop with two thunderbolt 2 ports (MacBook Pro retina 13 inch) and Sonnet Echo Express SE II so I can enjoy the full PCI-E 2.0 x4 speed and with a possibility to use two graphics card if I use PCI-E risers and an external power supply. Corning has just released 33 feet optical thunderbolt cables which enables all the noisy hardware to be further away from me. But that is another blog post when the money is there

UPDATE 08-01-2014: Added pictures of the setup

UPDATE 25-05-2014: Upgraded the setup to thunderbolt 2, see my post here

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14 Comments

Poul Serek

Pictures added to the article, yes it is not pretty, but with the new 10 meters thunderbolt cables available from the states, this noisy part of the setup can be in the other room

Stavros

I see.. I had something completely different in my mind.. So, it’s not a full docking station, but merely a thunderbolt cable connecting the laptop to a SuperBox.. hmmm.. Interesting..

Poul Serek

Well you can just connect this and have a full dockingstation since you can daisy chain thunderbolt devices. Or connect an Apple monitor which can tunnel keyboard, mouse and ethernet through the same cable

nosl1w

Great DIY work!

I have a t430s as well and was wondering if you had any updates or recommendations in the last year, specifically with the AKiTiO Thunder 2 enclosure? Thanks!

Poul Serek

I still have my Lenovo t430s and I am using it with my AKiTiO setup, see my post here for the setup and here for my custom exoskeleton case for the whole thing.

Currently I would recommend the AKiTiO Thunder 2 since it gives you double the bandwidth since you will run at Thunderbolt 1 speeds and the whole setup half the price compared to the PE4L solution. You will loose the ability to delay the PCI card detection, but since upgrading to Windows 8.1 running as UEFI I have had no need for this, both in Optimus mode and using an external monitor. And if you use a powered riser as I have you don’t even need AKiTiOs power supply to power the whole thing, just your ATX PSU

If you want to take full advantage of the Thunderbolt 2 speeds even though you only have Thunderbolt 1, you might want to take a look into buying two AKiTiO boxes and running CrossFire / SLI. Since Thunderbolt 1 and Thunderbolt 2 have the same total bandwidth, the only difference is that Thunderbolt 2 lets you use the whole bandwidth for a single device. With two graphics cards you should get the same total bandwidth as a single card running at Thunderbolt 2 speeds. I have not done this yet so research it a bit more before going down this road :)

And one last thing, I would recommend to buy an eGPU friendly graphics cards, e.g. NVIDIA cards from EVGA. They are internally powered and it make it easier to work with in my experience

nosl1w

Thanks! I really appreciate all your advice.

Still trying to wrap my head around everything, but I’ll let you know how it goes when I get everything together (along with some questions if you don’t mind :))

Can’t wait for 1440p 144hz gaming!

nosl1w

My friend has an old EVGA 560ti I was going to use, is there a minimum PSU I need to power it?

Poul Serek

As far as I can see on the net the card itself should draw around 200 watts of power, so a good 300 watts PSU should be enough, you might want to consider er 400 watt PSU if you are going to overclock the card. The PSU should also have 2 PCI express 6 pin connecters (or use an adapter for this), but confirm this since it might very from card to card

Kenny

Hi, I love the work you’ve done on your blog. I too have a T430s with TB and I am planning on getting a AkiTio setup (currently run it with a PE4L). Your comments on dual GPU SLI taking advantage of the two lanes are interesting and I think I might want to test that out. However, I have heard that TB1 reserves the second lane only for display out data via display port and cannot be used for PCIe data. I was wondering if you knew anything about it and how I would go about testing whether this is true.

Cheers,

Kenny

Poul Serek

Hi Kenny

According to this post you can use both lanes for PCIe, but a single device can only access one lane at a time. So it should be possible, but I would recommend searching the net a bit more to confirm. Ask around at techinferno.com, they seem to have done much research in eGPUs. Here is a link to a post doing SLI over thunderbolt 2: https://www.techinferno.com/index.php?/forums/topic/5751-2013-13-mbp-gtx780ti-sli16gbps-tb2-sonnet-ee-sel-win81-squinks/.

I don’t know how to test this, but I would try the following:

You would need to have two thunderbolt devices where at least one should be able to max the bandwidth of a single channel. One way would be to have a GPU and a harddisk attached using the same thunderbolt 1 link. While running a benchmark on the GPU that saturates half the thunderbolt 1 bandwidth, try transferring a large file using the harddisk. If the hardest is using the same channel as the GPU and the GPU is saturating half the bandwidth you should see a drop in frame rates. If you do not see this drop then it should be using the second channel.

BListein

Hi Poul,

Is there any performance difference for the t430s eGPU setup when used with TB2 device like Akitio as compare to TB1 like the Sonnet?

Poul Serek

There should be no performance difference in theory since the T430s is a Thunderbolt 1 device and can only take advantage of 10Gbps of the 20Gbps total bandwidth per device. So with the T430s you will always only get 10Gbps with Thunderbolt 1 and 2 per device. If you already have a Thunderbolt 1 eGPU setup I would not upgrade until your laptop supports Thunderbolt 2 or soon Thunderbolt 3. Notice if you use two graphics cards in SLI, then you should get the same performance as a pure Thunderbolt 2 setup since you can now use the full bandwidth in Thunderbolt 1 since it is spread across two devices! I have not tested this myself, but it is on my todo list if I can get my hands on another GTX 970.

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