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USB3 using the USB3380 chip


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So, USB3 is a grown-up bus capable of carrying one PCIe 2.0 lane.

Not much... except that for $160+$GPUCOST you can drive an n-way ATI crossfire (sorry nVidia guys, no SLI) rig on vitually any USB3-equipped laptop.

Not quite the $140 for a 8Gbit link that the TH05 offered, but nevertheless a competitor for the 1-lane (PE4H/L) solutions.

Details here (at the almost-bottom of the page, in the cleverly hidden third tab of the "BUY IT NOW" section:

USB3380EVB *( USB3380 Evaluation Board )

Anyone want to buy one and bench it?

Two more USB3 eGPUs on macbook air on top of my sonnet thunderbolt rig. Could be cute.

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Did any of you actually hit the link or are you just regurgitating what you already know?

There's nothing that prevents this from happening.

If you can put a PCcard reader on USB, you're effectively putting a PCI controller at the end of a USB pipe.

This is not rocket surgery.

USB3380 *IS* an implementation of the asic solution you're proposing, and someone put it on a board much like TH05.

There's no hard reason why a GPU on such a bus wouldn't work (disregarding driver support for hot-plugging and the like).

(and before we got eGPUs running on thunderbolt, then too were were mountains of people saying "it can't be done because nobody ever has".)

Read the link, people.

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i don't think you understand exactly what a thunderbolt controller does. it maps pcie and mini dp commands at the application protocol layer onto thunderbolt packets to be sent over the thunderbolt interface. to perform this specific function, it has to have built in logic to do this. it is meant to carry native pcie and mini dp commands over the thunderbolt link and phy layers.

a usb3 controller that sits off a pcie gen3 bus doesn't do this. a host system will issue commands over pcie that get translated into usb3 commands such as reads and writes, but there is no specific mapping of pcie commands onto the usb3 protocol. this is because usb3 is meant to be a data transport protocol. pcie is meant to be both a command and data driven interface for non-coherent traffic. in some cases it's also used as a system interconnect.

to do what you want would require a completely custom solution. something like an egpu knows how to talk to a host system via pcie. if you cannot carry pcie commands encapsulated within a usb3 packet, it's not going to work. there are a lot of things that a thunderbolt controller does in order to present itself as a native pcie bridge controller within the system. a simple usb3 controller will not have this type of support buit in.

if you didn't have a custom asic solution to transparently map system resources and still make the egpu presentable to the BIOS/kernel/OS, you'd need a lot of low level software support in order to make this functional. the egpu's driver would probably have to change significantly.

to give you an example, when you use setpci to access pci configuration space and set the pcie BAR registers, you are doing this via a config access. a configuration access is a type of pcie command, and is actually legacy from the pci days. usb3 has no provision for doing this type of configuration access. it just doesn't exist. you'd have to encapsulate the entire config access command into a usb data packet, send it over, and have a usb->pcie translation solution strip off the usb3 protocol info to get the config access pcie command.

this is networking 101. like iscsi, you could probably have a software initiator, but at the end of the link (egpu), you will need a custom solution from single or multiple asics.

please read the thunderbolt technology primer. Thunderbolt? Technology: Technology Brief

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Per the bottom of Thunderbolt, USB 3.0 and PCIe 2.0 eGPU update is BPlus' advice on using their USB3380 for eGPU purposes:

We have already developed it and the product number is "USB3380". However, it is not suitable for PC consumers but for embedded system, because installed video card can not be used directly and lots of device driver modification is required, due to bus architecture difference between PCIe and USB3.0.

The USB3380 is available at PLX or PLX's distributors, however we still recommended except for embedded systems.

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In basic networking courses you learn the concept of layering. Phy, link, protocol, and app layers. It's the typical OSI model that many networking protocols follow. This is what I meant.

Thunderbolt and pcie build on this concept. Pcie uses thunderbolt to replace it's phy layer and sort of gets pushed up into the application layer due the encapsulation thunderbolt provides.

This is possible because the thunderbolt controller has specific logic provisioned to perform this functionality transparent to any system with pcie.

This USB controller doesn't have this at all. You could theoretically have a software initiator that could form pcie commands and use the host CPU to encapsulate it within a USB3 packet to deliver over a USB3 phy, but that would be really slow and require custom software. Microsoft does this with their iSCSI software initiator. http://www.microsoft.com/en-us/download/details.aspx?id=18986

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It adds an USB 3.0 Port ... just like the productpage says.

... there is a second half to this sentence..

"...as well as convert an existing PCI Express function (endpoint) to a USB 3.0 product."

Go to the second-last frame on the page (USB3380EVB *( USB3380 Evaluation Board ))

The one with a BLUE-on-BLUE heading that says (you can see only if you select it) "Buy It Now".

(Whoever did this website needs to be shot. Multiple times. In the kneecaps.)

Under it are four tabs. Select the THIRD one that reads "USB3380-AB EVK-RC"

This is a board that

[a] Fits the 3380 controller card.

Fits a PCIe endpoint (the GPU).

[c] Through a driver (that may not exist yet), sends PCI commands and data to that GPU over USB3.

So I actually think the hardware does exactly what you're suggesting you need hardware to be able to do.

I just think it may (or may not) be $4k on freelancer for a functional windows driver away.


Plus, there's a friggin video of a guy connecting a USB3380-AB EVK-RC with a GPU in it to a monitor on one side and a laptop (via USB3) on the other, and it works.

Pray let us continue arguing over how this is theoretically impossible.

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I've got two MBA's with a sonnet and a TH05 respectively.

This wouldn't offer me much value for money, other than if

[a]. it actually works

I splashed out on two of these, three ATI cards (one for TB and two for the two USB3 ports) and ran a 3-way crossfire rig (would definitely be cool if it worked). But I'm not going to do that.

It could be a cool way to turn a surface-pro into a functional (even if somewhat RAM-restricted) game box.

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  • 9 months later...
Did anyone ever test this? About to buy a new laptop and the best option doesn't have an ExpressCard slot, so this would be great if it was possible.

It's not going to work. The videos on BPlus page showing a a video card attached via USB 3.0 is using an old S3 video card with heavily modified drivers to get it to work. Most sensible option is to either get an expresscard-equipped notebook or one that has an accessible mPCIe slot. The following may help you with your notebook purchase: http://forum.techinferno.com/diy-e-gpu-projects/4109-egpu-candidate-system-list-%5Bthin-light%5D.html#post57159

FYI: 15.6" Lenovo L540 is probably the most cost-effective eGPU friendly Haswell notebook. Has expresscard slot, i7-quad option, FHD option, NGFF SSD slot for possible future (faster x4 eGPU implementation ?? - we are not sure of pinout for this just yet), an iGPU for Optimus/Virtu internal LCD mode and of course the expresscard slot. Starts at $608 in basic i3-form : ThinkPad L540 | Mainstream Performer With Aggressive Pricing Optimized for Windows 8 | | Lenovo (US)

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FYI: 15.6" Lenovo L540 is probably the most cost-effective eGPU friendly Haswell notebook. Has expresscard slot, i7-quad option, FHD option, NGFF SSD slot for possible future (faster x4 eGPU implementation ?? - we are not sure of pinout for this just yet), an iGPU for Optimus/Virtu internal LCD mode and of course the expresscard slot. Starts at $608 in basic i3-form : ThinkPad L540 | Mainstream Performer With Aggressive Pricing Optimized for Windows 8 | | Lenovo (US)

Thanks for the tip. I'd seen your "eGPU candidate system list" before, and it was a useful guide. I was hoping to get something at or under 2kg though, which rules out that Lenovo L540. The MacBook Retina ticks most of the boxes, but as a Windows user it does seem slightly perverse to be buying a mac to install Windows (not least in terms of price). So instead I was looking at Dell's clone of it, the XPS 15 or the M3800. These have the wi-fi card in the NGFF slot, so even that won't be a possible route for upgrades.

Other options I'm considering are the Dell e7440, which does seem to have an ExpressCard slot, (confirmation from Dell still pending), but doesn't have a quad core option. The Lenovo T440s and T440p are also options, but again lack ExpressCard slots.

Given the chipset supports ThunderBolt, it's a pain that these don't have a ThunderBolt port...

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  • 4 weeks later...
EC03 (ExpressCard 2.0 to USB 3.0) USB interface

this is clearly a usb3 to expresscard adapter, does this work or we have to use mpcie from the insides of our pc?

Expresscard has pci-e and USB on it. That adapter simply allows a USB-only expresscard device to be routed to a USB port on a system. eGPUs need the pci-e component of a mPCIe/expresscard slot so that adapter is useless for eGPU connectivity. If you have no expresscard slot then your only (current) means of attaching an eGPU is via the mPCIe (wifi) slot.

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  • 1 year later...

Hi, I was reading some stuff about usb 3380 chip on internet and I found this device from hwtools: USB3380EVB *(USB3380 Evaluation Board) the device provides a powered pci-e slot and it comes with a DC power adapter and some aditional cables.

Did anybody try this?

EDIT: It seems to be the same thing as in this thread, sorry for any false hope.

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Hi, I had this little bit crazy idea, if we could create software that would simulate graphics card which would be connected to usb device. Basicaly software would make pc think that card is connected in pci-e slot and read all comunication that graphics driver sends through pci-e to graphics card, pack it into packages and send it over the usb to the device a programed chip would decode the package back to pci-e comunication and send it to the graphics card. Then the chip would pack all comunication from graphics card into a package and send it back, software would decode it and present the message from graphics card in the simulated pci-e device.

I don't know if it is possible to simulate a pci-e device, but I think it could be done by modifying systems core like linux kernel (I'm not sure about that.), but if you would simulate the graphics card there would be no need for custom driver, I think that is why usb3380 chip isn't used yet for egpu, because there would be driver issues.

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  • 10 months later...

Hi all,

I have a HP Envy 15 K-039TX and I would like to add an external graphics card to my laptop. However, my computer does not have a PCI-E slot, so I am not able to directly connect a desktop graphics card. What I would like to know is: Is it possible to connect a graphics card through a USB 3.0 port (I.E. a USB 3.0 to PCI-E adapter)? I have seen this page: How to use an external graphics card with a laptop, and I have also seen this adapter which i am not sure if I could use for this purpose: PCI-E USB 3.0 1X to 16X Extension Cable - Free Shipping - DealExtreme All answers are greatly appreciated. Thanks in advance,

Kind Regards,


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@wreckingball696: USB 3 can't be used for GPUs in a "good" way. Too many limitations are not allowing you that. In the last picture of the product you linked you can see that there is the "other side" of the USB connection, which goes into the laptop PCIe port. So USB 3 is here only the type of cable to connect the two PCBs used here. I doubt that they even use a USB chip or protocol and just use the lanes/wires of the cable.

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  • 3 months later...

Sorry for such a noob question ,but I'm still researching about which eGPU setup I want to go with and this is a new concept for me.  My question is, is it possible to connect an eGPU using USB 3.0 to a laptop?  My laptop doesn't support USB 3.0, but I did find out that a docking station for my laptop will allow me to, and since my laptop only has a first gen express card slot I think it will be a faster connection to go with USB 3.0.  Thanks in advance for any help.  By the way my laptop is the Dell E6420 in case that helps. 

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