DIY: Building your own external GPU for a MBA...

[pelov]

Lenovo's Y500/400 have ultrabay slots that you can plop a GPU into.

The above is a way better solution. Having a standardized slot that manufacturers can accommodate for would be even better.

 

[fralexandr]

sony viao z did an external gpu commercially back in 2011
http://www.anandtech.com/show/4474/sony-updates-vaio-z-thinner-lighter-light-peak-and-external-gpu
sadly it was only a 6650m

I was also expecting an actual built GPU, and not an adapter. diy egpu's are kind of silly from a portability standpoint, considering you could do better with a "lanbox" (hey you've got a PSU + GPU anyway, and the added adapter and notebook all add parts and take up space).

 

[Anonemous]

ok... maybe I misunderstand but there were people out there that were expecting the article to build an actual GPU as a DIY project?

just like people 'build PCs' but they don't go microfabricating the CPU...

 

[fralexandr]

ok... maybe I misunderstand but there were people out there that were expecting the article to build an actual GPU as a DIY project?

just like people 'build PCs' but they don't go microfabricating the CPU...

I wasn't expecting anything capable of playing modern games or anything... maybe something capable of displaying dos or something

 

[yh125d]

Lenovo's Y500/400 have ultrabay slots that you can plop a GPU into.

The above is a way better solution. Having a standardized slot that manufacturers can accommodate for would be even better.

While neat, if you have to buy a computer with a slot to accommodate the GPU, why not just get a laptop with the GPU already? With switchable graphics now you're not really losing much battery life by having the GPU all the time, and you're still limited by the chassis size/power for how powerful a GPU you can get.

If they worked towards OS support for eGPU rendering through thunderbolt or something then you could attach whatever you want

Just imagine if AMD and Corsair teamed up to put a 7850 and a special PSU in a case maybe the size of a large external HD. 8"x6"x2" or so with a thunderbolt interface, for $250? No idea what the market would be like for it but I'd probably consider one.

And that'd be pretty fast too. The fastest IGPs now are still slower than like a GT640 right? Throw a GTX650/7750 in a small semi-portable package for maybe $75-100 over the price of a standard card I'd buy one sight unseen



Could something like eSATA theoretically be used for input to the eGPU? Maybe WiDi for output either back to the laptop or external display?

 

[pelov]

The purpose of the ultrabay slot isn't just to hold the GPU, but it also doubles as a DVD/Blu-ray slot and can even accommodate an additional battery. The Y500 actually has two ultrabay slots meaning one can have SLi on a laptop via ultrabay GPUs.

eGPUs make the most sense for people who use a single laptop as their portable and desktop PC. Thunderbolt/WiDi aren't the answer, though. Proprietary connectors only lead to proprietary pricing and proprietary availability.

 

[yh125d]

The purpose of the ultrabay slot isn't just to hold the GPU, but it also doubles as a DVD/Blu-ray slot and can even accommodate an additional battery. The Y500 actually has two ultrabay slots meaning one can have SLi on a laptop via ultrabay GPUs.

eGPUs make the most sense for people who use a single laptop as their portable and desktop PC. Thunderbolt/WiDi aren't the answer, though. Proprietary connectors only lead to proprietary pricing and proprietary availability.

Yeah but you're still stuck with mobile GPUs and a laptop sized to accommodate. The OP's setup with a macbook air is about a perfect example of why a truly external GPU is desirable. The ultrabay, while cool, isn't really any different to use than any standard laptop with a dedicated GPU.

 

[pelov]

The ultrabay, while cool, isn't really any different to use than any standard laptop with a dedicated GPU.

That's the point, I reckon 😛 external GPUs make sense only for a smaller portion of people who would use a laptop as their main PC and their portable machine.

Personally, I like the idea. Plugging in my day-to-day laptop to use as my desktop rig would be awesome, but thunderbolt, usb 3.0 and pcie-to-whatever aren't worth the trouble.

 

[Aikouka]

Thunderbolt is PCI-E + DisplayPort, which is most likely how the video feed is being sent back.

 

[Rakehellion]

He did use the most current MBA. In the forum guide the author posted that he used a top of the line 11 in. MBA equipped with a Haswell chip (HD5000).

I know. The most recent model has native PCIe, so he could have used that instead of Thunderbolt.

 

[kt]

All that work just so you could play games on a 11-inch screen? No thanx.

 

[yhelothar]

Um, no not at all.

This is like being able to own and use a nice, thin, quiet ultrabook laptop and then when you feel like sitting at a desk and doing some gaming, you plug in the video card and game away. No need to always have a 5+ pound 15" behemoth rig at all times.

Or you could get a behemoth rig and keep it there. Use a super thin and lightweight laptop and remote desktop to the mainframe. Desktop power in a laptop. And just go back to your desktop when you want to game.

 

[slashbinslashbash]

Thunderbolt is PCI-E + DisplayPort, which is most likely how the video feed is being sent back.

My first thought was that the video signal was carried over the DP link as well, but apparently not.... my reading from this is that it's carried over PCI-E:

A decision you'll need to make is if you want to plug a monitor into your video card or just use your laptop's monitor. Each has it's own pros and cons. You'll get faster performance with an external monitor, but you'll lose the convenience of not needing a giant monitor. This becomes relevant as people make better eGPU cases where your eGPU will be portable. Why bring a monitor to your friend's place when your laptop already has one?

It's actually kind of cool that you even get this choice. The way it works is by the NVidia Optimus drivers taking the video frame memory from the video card, piping it back over the Thunderbolt bridge to the Intel HD 5000 memory and overwriting Intel's memory so that you see the eGPU's output on the Intel LCD. Cool! If you're curious, this is the exact tech that's used when laptops have an NVidia internal discreet graphics chip.

Which makes perfect sense, of course, and eliminates my confusion as to how the whole thing was being accomplished. To the MBA's CPU/chipset, the eGPU is just another PCI-E attached device. The eGPU can communicate bi-directionally over PCI-E to anything else on the PCI-E bus, exactly as if it were an internal GPU. That's the whole point, of course.

My main point of confusion was that I didn't think about the software and driver magic that allows machines to have switchable dual GPU's... I was thinking that the DisplayPort aspect of Thunderbolt had to be involved somehow, but apparently it isn't. The Intel integrated GPU is directly connected to the LCD, and the discrete GPU sends its info into the display buffer of the Intel GPU. That's..... really cool that it can do that.

To those talking about USB being able to do this.... I really don't think so. Think about all the communication that goes on between the CPU and GPU; you want that link to be as direct as possible. A USB layer is just an intermediary that would add lag. I'm sure it's possible, but it would probably give pretty poor performance. Remember, there's two aspects of a speedy connection: bandwidth and latency. USB 3.0 might have plenty of bandwidth, but I would bet that its latency is orders of magnitude slower than PCI-E. This doesn't make much of a difference in mass storage or network communications (where the lag is inherently greater) but CPU and GPU have been very tightly coupled all the way back to the AGP days.

 

[Anonemous]

My first thought was that the video signal was carried over the DP link as well, but apparently not.... my reading from this is that it's carried over PCI-E:

My main point of confusion was that I didn't think about the software and driver magic that allows machines to have switchable dual GPU's... I was thinking that the DisplayPort aspect of Thunderbolt had to be involved somehow, but apparently it isn't. The Intel integrated GPU is directly connected to the LCD, and the discrete GPU sends its info into the display buffer of the Intel GPU. That's..... really cool that it can do that.

huh, that's a pretty neat trick.

 

[Aikouka]

Which makes perfect sense, of course, and eliminates my confusion as to how the whole thing was being accomplished. To the MBA's CPU/chipset, the eGPU is just another PCI-E attached device. The eGPU can communicate bi-directionally over PCI-E to anything else on the PCI-E bus, exactly as if it were an internal GPU. That's the whole point, of course.

That came to mind since it's really the same as Optimus, but I wasn't sure if the really low bandwidth (5Gbps ~= 650MB/s ~= PCI-E 2.0 "1.5"x) would be even worse if you tried to transfer the frame buffer over it. I mean... to do a little math:

MBA 11": 1366W * 768H * 32-bit * 60Hz / 8 (b per B) / 1024 (B per KB) / 1024 (KB per MB) = 240MB/s

MBA 13": 1440W * 900H * 32-bit * 60Hz / 8 (b per B) / 1024 (B per KB) / 1024 (KB per MB) = 297MB/s

In other words, that alone is eating up around 1/3 of your bandwidth. :\

 

[slashbinslashbash]

That came to mind since it's really the same as Optimus, but I wasn't sure if the really low bandwidth (5Gbps ~= 650MB/s ~= PCI-E 2.0 "1.5"x) would be even worse if you tried to transfer the frame buffer over it. I mean... to do a little math:

MBA 11": 1366W * 768H * 32-bit * 60Hz / 8 (b per B) / 1024 (B per KB) / 1024 (KB per MB) = 240MB/s

MBA 13": 1440W * 900H * 32-bit * 60Hz / 8 (b per B) / 1024 (B per KB) / 1024 (KB per MB) = 297MB/s

In other words, that alone is eating up around 1/3 of your bandwidth. :\

Well, as Anonemous pointed out above, the guy's benchmarks show anywhere from 20% to 70% improvement when using an external monitor rather than the MBA's internal LCD. It's obviously not optimal, but it's awesome that it's possible, and not just possible, but actually gives reasonable framerates.

 

[PingSpike]

More like Intel. They don't want eGPU to be used over TB for some reason...$$$

Of course they wouldn't. Intel doesn't sell discrete GPUs. I'm sure they'd shut the door on PCI-E video card entirely if it were possible at this point.

Anyway, I find thunderbolt pointless for the same reason I found those proprietary external GPU interfaces that never came to light pointless. If the interface isn't available on your average craptop then it becomes an option only for more expensive setups...which means it only competes with people who are capable of buying a laptop with an onboard high end GPU already. So it only applies to a tiny part of the market that already has options. Being able to play games at home through your shitty laptop (because lets face it, most games are GPU limited and will still run fine a craptop CPU) is where this is a game changer. But those are precisely the systems that lack exotic interfaces that are required to do the job. Do you think thunderbolt is coming to your acer $300 special? I don't, and I don't even think its coming to midrange setups. Unless you could get USB3 doing it or an external PCI-E port becomes common on all machines its still going to be a niche product.

 

[Red Storm]

Or you could get a behemoth rig and keep it there. Use a super thin and lightweight laptop and remote desktop to the mainframe. Desktop power in a laptop. And just go back to your desktop when you want to game.

Why would I want to do that? I want a powerful, fast, thin laptop that does everything but play games well, and for the gaming need you just plug in an external GPU.

Note, this tech is for people that don't want big laptops. Those suggesting to get a big laptop should realize this isn't for them.

 

[Juddog]

Lame. The current MacBook air has an internal PCIe bus, which is what I was hoping he used. Show me the video of someone doing that. Thunderbolt adapters can be readily purchased online.

And no, USB 3.0 doesn't have the proper timing circuitry.

Thunderbolt basically is a PCIe bus over a wire with some bandwidth set aside for displayport.

 

[Rakehellion]

1. You can go to the store and buy a Thunderbolt to PCIe adapter.
2. Apparently, he used some store-bought components to make his machine.

Where's the care?

 

[Anonemous]

1. You can go to the store and buy a Thunderbolt to PCIe adapter.
2. Apparently, he used some store-bought components to make his machine.

Where's the care?

It's true he used off the shelf components. But the Thunderbolt to PCIe adapter that you listed has some limitations...

This is the product you found. It's a bit more expensive than what the guy used but let's say you bought it. http://www.sweetwater.com/store/det...g&matchtype=&gclid=CJbZzq6k2LgCFdKj4AodnTIAuQ

PCIe to Thunderbolt Expansion Chassis, with 1 x Slot for Half-length, Full-height, Single-width PCIe 2.0 Card

So there goes about half to most of your high performance GPUs... not to mention the non existence of a pci-delay switch (necessary for this hack to work) and an under powered psu.

And the author of the article does address this in his updated post.

Note that Sonnet also sells a faster 10Gbps Thunderbolt->PCIExpress box (~US$310 Sonnet Echo Express SE) which might seem like a great idea, but that's all sorts of problems with it, including an underpowered power supply, no PCI Delay switch (making it not easily work with Windows) and dismantling it to be able to use full length and double width video cards.

Now this product may work as pointed out in the later posts in that forum thread. $250 MSRP but it'll come out soon.
http://www.bit-tech.net/news/hardware/2013/06/06/silverstone-external-graphics-card-case-deb/1