15" MBP GT750m + GTX980@16Gbps-TB2 (Thunder2) + Ammo Case + W10/macOS 10.12 Sierra

[P-Mac]

 

This isn't even my final form!

"DotPusher III" 

 

Hardware:

• Mid-2014 MacBook Pro (15-inch)
  • Core i7-4980HQ (2.8 GHz)
  • NVIDIA GT 750m
• NVIDIA TITAN Xp 12GB (GP102-450) (previously 980, 980 Ti)
• Also tested with: EVGA GTX 1080 SC (see bottom of post)
• Akitio Thunder2
• Corsair 550w ATX PSU
• "Fat .50" Ammo Can (800 rd 5.56mm)

 

Software:

• Windows 10
• Latest macOS version
• automate-eGPU.sh
• rEFInd Boot Manager
• apple_set_os EFI application

 

Tools:

• Screwdrivers
• Channel-lock Pliers (or vise grips)
• Jigsaw / Dremel / Angle Grinder / Metal File / Sandpaper

 

The Build

Honestly, the build was surprisingly simple! Popped open the Akitio, used channel-lock pliers to pry the front side of the Akitio open to allow for the length of the GPU. Added gaff tape over all of the metal parts, just in case the card came into contact with the bare metal of the bent Akitio enclosure. 

 

Got the card handy, a gorgeous little reference model GeForce GTX 980.

Spoiler

 

 

 

 

 

 

 

On a side note, I actually had an MSI GTX 980 GAMING 4G but ended up trading it for this reference unit, as it was one of the ugliest pieces of hardware I've ever seen, and the reference models are just beautiful. (Form over function, but isn't that the Apple way? :P)

 

The card slotted right in, no problems here.

Spoiler

 

 

 

 

 

Next up was the power supply. I used a Corsair 550w unit, but cut everything besides the two PCIe power connectors and the CPU 12v rail (to power the Akitio). Terminated all the ends with shrink wrap and gaff tape on top of that, and taped all the unused lines down to the side of the PSU. It was also during this step where I hotwired the PSU to always be "on" via the paperclip trick...except I just traced those wires back to where I was going to make my cut, and soldered them together.

 

For the Akitio's power, I used the molex-to-barrel-adapter guide, but instead of being patient and getting a proper barrel connector with two leads, I cut the barrel connector off of the Akitio's power supply that came in the box. I like to live life in the moment, I guess...but the fruits of my labor were revealed when I stripped the wire and it turned out to be coaxial instead of side-by-side! No matter, I said to myself, as I twisted the outer fibers into a solderable piece of wire, and stripped the inner wire as well. Verified polarity via a multimeter, and soldered the Akitio barrel connector to the CPU12v line from the PSU. A bit of shrink-wrap and gaff tape later, and I had a nice little feed for the Akitio coming off of the PSU. 

 

No powered riser bs, no extra Akitio power supply. Clean and simple. PCIe plugs went straight into the GPU, I gave em a little bend so they'd hug the edge of the magazine holder. I also re-routed the front LED from the Akitio's box around the back of the PCB to where the Akitio power plug is, so that that area of the magazine holder lights up blue when the card is active. 

Spoiler

 

 

 

 

 

 

 

At this point, I took the magazine holder and made cutouts for the GPU ports, ventilation, and PSU ventilation. Covered the rough edges with gaff tape so they wouldn't fray and get sucked into a fan (plus it looks a bit less janky). The Akitio with GPU slid perfectly into one side of the magazine holder (make your measurements first before going shopping!), but was sitting too low for my cutout to be centered on the GPU's cooler...nothing a little packing foam (from the Akitio box!) couldn't fix. 

 

The PSU slid in with...some effort. 

Spoiler

 

 

 

 

 

 

 

From my measurements, I knew the PSU wasn't necessarily going to fit, but it was close enough that with a bunch of gaff tape to keep the bottom and sides secure, it doesn't move anywhere and there are no signs of any danger of it falling out after a good 2 weeks with the setup. I just try to keep this side hidden, it's pretty garish. 

 

EDIT 070416 (MURICA DAY)

 

Added green underlighting because #AMDsux #teamNVIDIA (lol). Here she is at work (literally, at my work), powering 2x 120 Hz displays & a bunch of OpenCL compute.

 

Spoiler

 

The Experience

It was time to start her up. Plugged in PSU, switched it on, plugged my 4K 60Hz monitor into the eGPU, plugged the TB cable into the Mac and hit the power button. Fired right up, booted into Windows and re-installed the NVIDIA drivers. After a reboot, the card was recognized, and I was playing Doom (2016) at ultra quality 1440p inside of 10 minutes. Not too shabby! 

 

I spent some time in MSI Afterburner, customizing a fan curve to keep it pretty quiet during moderately high gaming workloads, but ramp the fans up quickly if the temperature went north of 70º C. Boy, this thing is loud when the fans are at full tilt, but I'm glad they; the reference cooler is no slouch, and with fans cranked to max it's actually able to pull down the temperature from 80 down to 70 while furmarking! 

 

With a bit of tinkering, I settled on a final, furmark-for-8-hours-stable overclock of +225 MHz core, and 7400 MHz on the memory. Using ThrottleStop, I also undervolted the i7 in the laptop, and downclocked it to ~2.4 GHz. Windows runs a bit hotter than OS X, figured I'd help out as much as I could. 

 

I gotta say, it feels good to put down an 80th-percentile score in 3Dmark Fire Strike with a MacBook Pro.

 

On the OS X side of things, automate-eGPU.sh took care of everything without a hitch. I did notice some weird stuttering every second (and exactly on every second), but with some tinkering I found out that the "Displays have separate spaces" option was the cause of the issue. Disabling it made OS X run perfectly smoothly afterwards.

 

Final Cut Pro X immediately took advantage of the new GPU, and I was able to play back Sony FS5/A7s 4K footage with a few layers of colorgrading on it much smoother than with the 750m. It can almost handle playing it back at full-res, which was just astonishing to me. Analyzation of footage for stabilization just rips, along with optical flow retiming. 

 

Adobe CC was able to take advantage of the card as well, Mercury Playback Engine (CUDA) felt much smoother than on the 750m, though I haven't been using Premiere in a while so I didn't do much testing in CC. Unfortunately, After Effects is not really accelerated by the card, but oh well. 

 

To get Optimus to work with a 750m-equipped MacBook Pro, I turned to this reddit thread detailing the installation of rEFInd and using an EFI utility called apple_set_os to get the Mac to expose the Iris Pro when booted into Windows. I also customized the rEFInd interface because the default skin looked like something out of Mac OS 7.5.3 (I half expected little puzzle piece extension icons to start loading across the bottom).

Spoiler

 

 

 

 

 

 

The reasoning for using apple_set_os instead of the built-in spoofing feature in rEFInd is because I'd like to normally run Windows without the iGPU enabled, but retain the ability to switch into "Optimus mode" when I'm mobile.

 

My full boot/setup process for mobile gaming via Optimus, coming from normal eGPU usage with external monitor is as follows:

1. Leave eGPU unplugged
2. Boot into Windows
3. Disable the 750m in Device Manager (I usually leave it enabled when booting Windows normally)
4. Run the switch-GPU script to set the iGPU as primary
5. Shut down Windows
6. Plug in eGPU and start the computer
7. Select apple_set_os (I've renamed this to "iGPU Enabler", the far right icon in rEFInd)
8. Boot Windows

 

If all goes well, I'm in Windows with the GTX 980 as the Optimus "high-performance NVIDIA processor". Game performance takes a bit of a hit, but not anything significant...I can still play most titles at 1080p ultra quality, and they look great on the MacBook Pro's retina IPS display. 

 

Lingering Issues

Thankfully, all of the lingering issues I have only involve the boot process. Sometimes the entire system refuses to POST (sits at a black screen without ever chiming), and I have to hold the power button for a few seconds and try again. When it does POST though, the next hurdle is whether the driver (in OS X or Windows) will initialize properly. Sometimes it doesn't want to play nice, and I'll get a BSOD on booting Windows with DRIVER_IRQL_LESS_OR_NOT_EQUAL, but a restart or two will do the trick.

 

FIX FOR BSOD ON BOOT: I figured it out, a trip to Device Manager and I noticed there was a "show hidden items" menu option. Clicking that revealed that I had two GTX 980 devices that weren't connected for some reason, and the driver was fighting itself upon initialization during boot. Rebooted into Safe Mode and ran DDU to clean out the NVIDIA driver, reinstalled it in normal mode with the eGPU connected, and all is well. One GT 750m, and one GTX 980 in Device Manager when viewing hidden devices. If you're having driver issues like I did, you might want to check this.

 

(NEW) FIX FOR macOS NOT BOOTING: Run Goalque's script in "-a mode". This alters something regarding the thunderbolt chipset on every shutdown, so when rebooting back into macOS, the eGPU will initialize properly every time. 

 

For OS X, I just get a black screen with my monitor showing no signal input. Again, a restart or two fixes this. (Honestly, I've had the NVIDIA Web Driver do this with the internal 750m, so it's just a normal driver-crashing-on-init issue, not specific to the eGPU.)

 

But once the system is booted, it is rock solid, and I've never had anything crash or fail (besides overclock-induced crashing in Windows, but that's my own fault).

 

It all seems to be based on luck of the draw, as I'll have some days where it'll work flawlessly and I'll be bouncing between the two OS's with no problem, other days I'll get 8 failed starts in a row. If anyone has any idea how to help mitigate these failed starts, I'm all ears.

 

The only other issue I can think of is lack of display brightness control when running in Optimus mode (anyone got any clues?), but it just means I have to set the brightness from within OS X first before going through the boot process. 

 

 

Final Thoughts

It was totally worth it. I'm in love with this setup, it truly feels like the best of both worlds. The i7-4980HQ in the MBP is no slouch of a CPU, the only thing my setup was missing was some graphics horsepower, and the GTX 980 more than comfortably steps up to the plate. My work experience has had amazing fluidity, and gaming has gone from sub-720p resolutions on the latest titles to gorgeous looking, maxed quality 1080p and higher. Less demanding titles (CSGO, Borderlands Pre-Sequel) even run at 4K 60fps, which is a sight to behold. The Oculus Rift that I got my hands on runs perfectly smooth, with no VR-sickness to speak of. And all this, in a "portable" setup. 

 

I now have 3 levels of portability (with associated levels of performance): full desktop mode, Optimus (so I don't have to lug a monitor around to LAN parties or remote editing / rendering of CGI), and of course the laptop by itself (which, with its Core i7, is still no slouch, at least when it comes to CPU compute power). 

 

It's also extended the longevity of my machine a lot, since I was looking at the 2015 and purported 2016 models for their GPU upgrades...but not anymore! The only thing I'm looking at is the moment NVIDIA releases Pascal drivers for OS X...and my poor wallet might have to take the brunt of a GTX 1080.

 

The Future

I'm still on the hunt for a better case, but all of the computer cases I've found are...well, computer cases, and far larger than this magazine file setup. So I'm looking at...different solutions. An old army surplus ammo box looks like my next case, and it has a handle at the top, which I can't live without after having this magazine file for a couple weeks. 

 

I'd love to pick up a modular SFX PSU so that the PSU actually fits into the magazine holder without any modification necessary, and if it's modular, it'll help keep the cables clean and tidy, with no drive and fan power cables to cut. 

 

Hope you guys enjoyed the adventure, and that some of the solutions to the little quirks I found help out someone! Happy eGPU-ing!

 

---

 

EDIT 070416 (MURICA DAY)

 

Just for kicks, slapped a buddy's GTX 1080 into the chassis to test with Windows. It required a driver reinstall as the system didn't detect the 1080, even after rebooting...it seems that the NVIDIA driver enumerates the cards in your system at install time and will only install the drivers it needs to, not all of them (different from the way OS X does it). The driver install worked fine without having to run DDU and cleanly install. YMMV though.

 

The added compute power of the GTX 1080 was more than welcome to help mitigate the performance hit you take when using Optimus. Crysis 3 ran at the laptop's native resolution (2880x1800) at around 45-60fps with all settings cranked. Beautiful. 

 

I was really looking forward to testing out Rise of the Tomb Raider on it, but ironically there's a bug with Pascal cards and NVIDIA VXAO, so I couldn't get a fair comparison.

 

Wish I could keep it, but the lack of Pascal drivers for OS X keeps me on the 980. For now.

 

Spoiler

 

 

 

EDIT 071816 

 

Acquired a "Fat .50" (actually an 800x 5.56mm) ammo box and made the primary cuts using a pneumatic angle grinder + cutoff wheel. Test fitted the Akitio and PSU. Currently need to drill the PSU & AKT mounting holes, but also trying to figure out what thread pitch the Akitio's mount holes are (anyone got a clue?). Specifically, the ones that the Akitio's own case's captive thumbscrews screw into. 

Spoiler

 

 

 

 

 

EDIT 072016

 

Finally finished the ammo can case after much measuring, cutting, and drilling.

 

Spoiler

 

As the barrel plug was going to be flush against the side of the case, and I didn't want to have to loopback the cable like I did in the magazine file, I ended up soldering the CPU12v rail to the back of the Akitio's PCB. Pre-tinned the wires and plopped them onto the PCB, then secured it with gaffer's. Verified the correct solder points thanks to /u/Dippyskoodlez, who found the info from these very forums. Singed the PCB a bit, but oh well, close enough.

 

Spoiler

 

 

 

EDIT 050517

NVIDIA released Pascal drivers for macOS. Upgraded eGPU to a TITAN Xp. Benchmarks available upon request.

Yes, it's completely a ridiculous setup now—I was only able to upgrade due to external circumstances. Diminishing returns starts to creep in (even for the much-more-fairly priced 1080 Ti) due to the TB2 bottleneck. 

Edited May 5, 2017 by P-Mac
added TXp upgrade

[JohnyB33]

Nice case, You had no issues when cutting all the other wires on the PSU? I want to do this to mine but was not sure if the cutting the wires that were not in use would affect the power supply.

[P-Mac]

4 hours ago, JohnyB33 said:

Nice case, You had no issues when cutting all the other wires on the PSU? I want to do this to mine but was not sure if the cutting the wires that were not in use would affect the power supply.

 

Nope, just be sure to terminate them individually, I went with both shrinkwrap and gaff tape just to be double sure, there's tons of mixed polarity in the ATX 20-pin connector and the last thing you want is two things shorting out. 

 

Electrically, the wires being cut and the wires not being connected to anything are the same, so the PSU "sees" nothing different. If it works with those wires not plugged into anything, it'll work if those wires are trimmed down. 

[murcielagoferrari]

Hi P-Mac, nice to meet you.

I read your post about setting up eGPU for MacBook Pro. I have made a similar set up for my MacBook Pro (same as yours). I used the same way as the steps you suggested. What I have so far is make the Mac runs on Iris Pro in Win 10 as primary. From device manager, I can see my eGPU, iGPU and disabled dGPU. But no matter what I did to any 3D apps, to let them run in high performance mode. But in internal display, it always uses iGPU. So I am wondering if you have any idea about it

 

[P-Mac]

2 hours ago, murcielagoferrari said:

Hi P-Mac, nice to meet you.

I read your post about setting up eGPU for MacBook Pro. I have made a similar set up for my MacBook Pro (same as yours). I used the same way as the steps you suggested. What I have so far is make the Mac runs on Iris Pro in Win 10 as primary. From device manager, I can see my eGPU, iGPU and disabled dGPU. But no matter what I did to any 3D apps, to let them run in high performance mode. But in internal display, it always uses iGPU. So I am wondering if you have any idea about it

 

 

 

If you've enabled "Use High-Performance NVIDIA Processor" in the NVIDIA Control Panel, but the apps are still using the iGPU, then I've got no idea. Sometimes apps do that (I had issues when running VR apps without a monitor attached to the eGPU). Wish I could help...

[P-Mac]

Found a fix for the Windows BSOD upon driver initialization during the boot process, added it into the main post. 

 

"I figured it out, a trip to Device Manager and I noticed there was a "show hidden items" menu option. Clicking that revealed that I had two GTX 980 devices that weren't connected for some reason, and the driver was fighting itself upon initialization during boot. Rebooted into Safe Mode and ran DDU to clean out the NVIDIA driver, reinstalled it in normal mode with the eGPU connected, and all is well. One GT 750m, and one GTX 980 in Device Manager when viewing hidden devices. If you're having driver issues like I did, you might want to check this."

[P-Mac]

3 hours ago, igloo_si said:

Hey, Ihow diy you find enough usb3 ports to power oculus rift on mbp?

 

4-port USB3 hub. 

[chlgmlco1346]

Hello!

i have macbook pro (same model as you have),and i'm having trouble with eGPU.

i bought all the thing that i need.

but when i turn on windows 10, my macbook catch both GPU.(gt 750m,gtx 950)

And i read all your tutorial,but i'm not professional.

So i have to ask something about this.

 

first, i have to apologize that i'm not good at english.

please under stand that.

 

I wanted to ask,

how to use 

• automate-eGPU.sh
• rEFInd Boot Manager
• apple_set_os EFI application

this three things??

from installing those things.

 

and when i do correctly,

will it only work for external display??

is there anything solutions for internal display??

[chlgmlco1346]

OK,I almost got it.

please tell me how to copy apple_set_os.efi file in my rEFInd partition??

 

please teach me....

please.....

[P-Mac]

run mountesp in terminal to mount the EFI System Partition, and then follow the instructions on copying apple_set_os.efi

[Morv]

This ammo box case is damn cool, I think I'm gonna rebuild that  They're also pretty cheap on eBay but they are like the best thing for an eGPU regarding form factor. Awesome work!

[chlgmlco1346]

3 hours ago, P-Mac said:

run mountesp in terminal to mount the EFI System Partition, and then follow the instructions on copying apple_set_os.efi

I can boot to rEFInd,but i can't find apple_set_os boot...

[chlgmlco1346]

3 hours ago, Morv said:

This ammo box case is damn cool, I think I'm gonna rebuild that  They're also pretty cheap on eBay but they are like the best thing for an eGPU regarding form factor. Awesome work!

How can i copy that file??

With terminal?

[P-Mac]

5 hours ago, chlgmlco1346 said:

How can i copy that file??

With terminal?

 

Please read the directions marked on the apple_set_os github page by the author. 

 

You need to perform this after you've successfully mounted the EFI partition, which you can do using "sudo mountesp" if you've properly installed rEFInd. 

 

You might also need to modify the path a bit, should be /Volumes/ESP/EFI/custom

 

If you are unfamiliar with basic terminal commands I suggest you do some research on how to perform basic tasks like creating directories and copying files using a UNIX terminal. 

Edited July 21, 2016 by P-Mac

[chlgmlco1346]

On 2016. 7. 22. at 1:40 AM, P-Mac said:

 

Please read the directions marked on the apple_set_os github page by the author. 

 

You need to perform this after you've successfully mounted the EFI partition, which you can do using "sudo mountesp" if you've properly installed rEFInd. 

 

You might also need to modify the path a bit, should be /Volumes/ESP/EFI/custom

 

If you are unfamiliar with basic terminal commands I suggest you do some research on how to perform basic tasks like creating directories and copying files using a UNIX terminal. 

Thak you for your instruction!

I did it!

But i have a problem.

I turn on the igpu with gpu-switch,and reboot to EFI and use apple_set_os.efi,sometimes,it froze.

Espacially when i pluged egpu.

Do you have any clue?

 

And do i have to do your boot instruction every time when i boot to windows?

 

Thank you for your help!

[UncleGravity]

Hey @P-Mac, sick write-up.  I followed it to a T got almost everything working.  Have you actually benchmarked the 980 while using the internal screen (Optimus)?  Optimus works perfectly with the 750m, but when I disable it/run gpu-switch/reboot with eGPU, it boots fine, but it doesn't actually use my eGPU because Optimus never kicks in.  If I try to open nvidia control panel, it says "You are not currently using a display attached to an NVIDIA GPU", so it doesn't open up.

 

I have the Akitio + GTX970, Macbook Pro mid-2014 w/ 750m, dual booting osx/windows (uefi), with latest rEFInd +  apple_set_os.  Intel drivers + nVidia drivers are installed and everything shows up in device manager correctly.  

 

If it works for you, it should work for me, since we both have the same set-up, so I'll know I'm not wasting my time trying to get Optimus to work.

[P-Mac]

3 hours ago, UncleGravity said:

Have you actually benchmarked the 980 while using the internal screen (Optimus)?

 

Hi, I haven't benchmarked, but I've played through many hours of Crysis 3 (1080p/High) and Rocket League using the 980 via Optimus, so I know it's working.

 

Is the NVIDIA Control Panel set to use "High-Performance NVIDIA Graphics"? Does the GTX 980 show up in Device Manager without any exclamation marks, along with the GT 750m (disabled) and the Intel Iris Pro? 

[UncleGravity]

Good to know.  Thanks for the quick reply.

 

The NVIDIA Control Panel shows up only when I boot with dGPU + Iris.  I can then set the 750m as the "High-Performance NVIDIA Graphics".  

 

The eGPU does show up correctly in device manager, no exclamation marks.  I boot-up looks like this:

 

1. Boot windows normally, egpu disconnected.

2. Disable 750m

3. Run gpu-switch (set to igpu)

4. Shutdown, plug-in egpu

5. Run apple_set_os

6. Start windows

 

After doing that if I open Device Manager, I can see the Iris Pro, the 750m (disabled), and the 970 (no exclamation), but if I try to open NVIDIA Control Panel, it just throws a dialog with "You are not currently using a display attached to an NVIDIA GPU", and it doesn't open the control panel.  So if I try to play, it only uses the Iris Pro and never switches (which, as you can imagine, is not ideal).

 

If I plug in an external monitor, it works great.  And Optimus works with the 750m + Iris, so that's fine too.  Not sure what I'm missing really.  I'm so close!

[P-Mac]

Hm, I would try reinstalling the NVIDIA driver while booted into Windows with the eGPU plugged in. It sounds like the driver hasn't been installed for your GTX 980, so even though it shows up in Device Manager, the NVIDIA driver won't see it.

[UncleGravity]

Hmm, after messing with the drivers for a while I noticed that the GTX 980 (the one you have) is listed in the list of devices for the nvidia "notebook" drivers, but my card isn't (gtx 970).  It's the only non mobile card on that list.  I guess that's because the full 980 (without the 'M' suffix) came out for laptops.  

 

http://www.nvidia.com/download/driverResults.aspx/105035/ (the device list is in the "supported products" tab)

 

I have a theory, and it might be silly, but perhaps the 980 is the only non mobile 900 card that would work with this setup.  I've seen people using the 1070 too so maybe the 1000 cards have that functionality.  I mean I'm just speculating, since I haven't seen anyone else make this work with a 970.

 

I don't have a 980, but I'll see if one of my friends does.  If you know someone with a 970 and can test it out, that would be sick.

[P-Mac]

3 hours ago, UncleGravity said:

If you know someone with a 970 and can test it out, that would be sick.

 

That thread is a confirmation of a 970 working via Optimus. The driver should not really care. Verify you're actually booting with the iGPU as the active card, run DDU to cleanly uninstall the nvidia drivers, and reinstall (booted normally with eGPU + external monitor, don't try to install the drivers while running in Optimus mode) the NVIDIA drivers. 

 

[UncleGravity]

Did it a few times.  Still nothing.  Do you think it has to do with the OS?  I'm using Windows 8.1.  I'll try upgrading to Windows 10 and see what happens.

 

I'm also using this bootcamp partition for Parallels so they have their drivers installed.  Not sure if that would mess anything up.

[Morv]

On 5.8.2016 at 9:04 PM, UncleGravity said:

Did it a few times.  Still nothing.  Do you think it has to do with the OS?  I'm using Windows 8.1.  I'll try upgrading to Windows 10 and see what happens.

 

I'm also using this bootcamp partition for Parallels so they have their drivers installed.  Not sure if that would mess anything up.

 

Don't install the mobile drivers but the usual desktop drivers for the GTX 970. Every desktop card works as an eGPU but you need the correct desktop driver. The mobile driver for the GTX 980 works for the desktop GTX 980 solely because it's actually the exact same chip in both versions only with lower clocks for the mobile version.

[P-Mac]

...there is no difference between the "mobile" driver and "desktop" driver, I've been using whatever the latest NVIDIA driver was for the internal GeForce cards since my 2012 MBP. Even the boot camp driver is a byte-for-byte installer (of an older driver) from NVIDIA's Driver Downloads. You do however have to have both cards active when you perform the install to get the driver to recognize and activate both internal and eGPU.

 

Parallels bootcamp drivers might be messing stuff up, and unfortunately I can't test much more for @unclegravity since I'm on Windows 10 1511 and not running any odd drivers like those. 

Edited August 7, 2016 by P-Mac

[UncleGravity]

I did a fresh install of Windows 10, installed all the latest drivers, and now I can open the nvidia control panel and I can see the "GPU Activity" panel in the toolbar, which is progress.  I've set the "Preferred Graphics Processor" to "High-performance NVIDIA processor".  Nothing seems to run on the eGPU though.  It always says "There are no applications running on this GPU", no matter what I throw at it.