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I've been thinking about buying a high-end ultabook, but since I'm a PC gamer, I'm worried about the performance. I've heard of USB graphic cards, but I'm unsure how well those perform.

If I buy an ultabook with USB3 ports and a external graphics card dock that supports USB3, will it be just as fast as if it where in my computer?

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A USB3 graphics card are several times slower then a grahic card connect to a PCIEx16 bus. – Ramhound Jul 2 '13 at 13:56
Interesting. That's kind of what I figured. What about something like Firewire or Thunderbolt (although I don't think Thunderbolt is available on a Windows machine)? – Rev Jul 2 '13 at 13:59
Firewire is several times slower then USB3. If you are able to afford an external Thunderbolt you might as well just purchase a ultrabook with a highend mobile graphics card. – Ramhound Jul 2 '13 at 14:05
up vote 4 down vote accepted

I've been thinking about buying a high-end ultrabook, but since I'm a PC gamer, I am worried about the performance. I've heard of USB graphic cards, but I am unsure how well those perform.

This depends on the graphics card, but the performance usually is a lot slower than those of a regular PCI-e graphics card.

Basically you have the following options:

  1. Build in graphics, e.g. in the APU, on the CPU die or via a dedicated graphics chip.
    This will work, but it will use a lot of power which is not compatible with the ultrabook (thin, very long battery life and low power parts).
  2. An external graphics card via USB 2: This will be slow.
  3. An external graphics card via USB 3: This should work. Not sure if it works well enough for gaming.
  4. An external graphics card via thunderbolt. This should work almost as well as a normal graphics card in a desktop because it will use a normal desktop graphics card. You usually only get an x4 or an x8 PCI-e connection (depending on the thunderbolt chip used) which will slow down graphics by a few percent. (How much depends per game, but 4% is a good guess).
  5. An external graphics card via the express card slot. Basically express card is USB plus a single PCI-e lane. Either with a very small card in the expresscard slot, or with a normal PCI-e graphics card and a convertor.
  6. Via a free mini PCI-e slot on the notebook. Assuming your BIOS supports it (a laptop BIOS's often does not) and assuming you have a free connector (also unlikely in an ultrabook where space is at a premium).
  7. A laptop with a docking station and either a free PCI-e slot in the dock of a build in graphics card in the dock. (Similar to the large docks of the Dell lattitude D-series).
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USB3 is as fast as Thunderbolt when only one card is used.....don't confuse USB2 with USB3.....also Firewire is as slow as USB2, so again, the most economical solution is a USB3 solution. Only problem is I havent' seen many such solutions that take advantage of the USB3 speeds.

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This answer is just wrong: USB 3.0 offers about 4Gbit/s in total, Thunderbolt 10Gbit/s in each direction, the next iteration will even have 20Gbit/s. Thunderbolt actually is a native PCIe connection, where USB-graphic cards have much more protocol levels in-between slowing things down and requiring the CPU to do more work. – Jens Erat Jun 24 '14 at 7:52

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