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DocMAX
April 18th 07, 08:21 PM
hi,

is it possible to build an external graphics accelerator connected to
usb 2.0? i think about speeding up actual laptop 3d solutions...

docmax

--

Stephen SM WONG
April 18th 07, 08:52 PM
Forget it! The 480 Mega Bits Per Second theoretical
bandwidth of a USB 2.0 port is just too limited to be useful
for today's graphic applications. The AGP 8X has a (33MHz
PCI x 4 bytes per bus width x 8) 1 Giga Bytes Per Second
bandwidth.

For example, if you want to draw a 1280x1024 frame (24-bit
color plus 8-bit alpha) 75 times a second, you need to move
around 400Mega Bytes a second to the frame buffer. And
then, if you want to have any acceleration, you need to move
extra texture maps, drawing primitives, direct X programs,
etc. to your graphics card.

Well, if you accept a 640x480x32 frame at 30Hz, the required
bandwidth is around 40 Mega Bytes Per Second, or 300 Mega
Bits Per Second, and the USB 2.0 bandwidth may barely
suffix.

My 2 cents.

Stephen Wong @ Hong Kong


On Thu, 18 Apr 2007, DocMAX wrote:

> hi,
>
> is it possible to build an external graphics accelerator connected to
> usb 2.0? i think about speeding up actual laptop 3d solutions...
>
> docmax
>
>

First of One[_2_]
April 19th 07, 12:39 AM
It's possible to build an external graphics adapter connected to USB 2.0,
and there are several products on the market. These are used to connect
multiple monitors for office productivity, not 3D. As Stephen pointed out,
the 60 MB/s bandwidth of USB 2.0 is just too limiting. A Voodoo3-class
accelerator may be able to survive with such limited bandwidth, but most
laptop integrated video solutions are faster than Voodoo3s nowadays.

--
"War is the continuation of politics by other means.
It can therefore be said that politics is war without
bloodshed while war is politics with bloodshed."

"DocMAX" > wrote in message
...
> hi,
>
> is it possible to build an external graphics accelerator connected to
> usb 2.0? i think about speeding up actual laptop 3d solutions...
>
> docmax
>
> --
>

Geoff
April 19th 07, 02:54 PM
"DocMAX" > wrote in message
...
> hi,
>
> is it possible to build an external graphics accelerator connected to
> usb 2.0? i think about speeding up actual laptop 3d solutions...
>
> docmax
>
> --
>

possible, yeah prob
would you wanna see how slow it ran?
not really