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Gauss
11-04-2004, 04:35 AM
On APG 8x graphics cards i measured upload speeds from CPU to GPU using Pixel Buffer Objetcs (PBO) up to
1800 MB/s
for 2d textures so here one comes pretty close to 2 GB/s, the theoretical limit.

However, on PCI-Express cards like a FX3400 from NVidia the theoretical limit would be 4 GB/s, nevertheless i measured that the PBO speed is even slower here
1300 MB/s (using the latest drivers).

Does anyone have yet found a PCI-Express graphic card/system combination that comes close to 4 GB/s when uploading data from CPU to GPU?

Relic
11-04-2004, 05:12 AM
Repeat after me: Never post "using the last drivers", always give a version number.
People cannot try the same things you do if you don't tell such important details.

Gauss
11-04-2004, 06:03 AM
Hi Relic,

i tried it with various drivers, e.g. starting from 61.77 up to 66.81 from the NVidia ftp side.

regards,
Gauss

Relic
11-04-2004, 07:53 AM
See? For the adventuresome there's already a 70.41 beta floating around. ;-) Don't know if it helps.
http://download.guru3d.com/detonator/

Korval
11-04-2004, 09:22 AM
However, on PCI-Express cards like a FX3400 from NVidia the theoretical limit would be 4 GB/s, nevertheless i measured that the PBO speed is even slower herenVidia cards that are PCIe capable are not really PCIe native. This means that, internally, they're still using some form of AGP. There's a piece of hardware that converts from AGP to PCIe, so you won't get the PCIe performance that you might expect.

Tzupy
11-05-2004, 04:25 AM
Hi,
It would be interesting to know the performance on a GeForce 6600 GT (native PCIe). AFAIK the Quadro FX 3400 is a NV 35 GL with HSB. I delayed the purchase of a GeForce 6800 GT (AGP 8x), waiting for a PCIe nVidia card and, of course, nForce4 mobo. I'm very interested about the read-back performance of a native PCIe nVidia card.

speedy gonzalez
11-05-2004, 05:05 AM
Hey guys FYI I also noticed a performance problem with the FX3400 card, this time using glTexSubImage2D:

http://www.opengl.org/discussion_boards/cgi_directory/ultimatebb.cgi?ubb=get_topic;f=3;t=012686

Hope Nvidia will fix this soon !

Gauss
11-05-2004, 06:56 AM
Hi Speedy,

you are right, using glTexSubImage2D i get not more then 185 MB/s with BGRA/RGBA and 340 MB/s with Luminance8/Luminance16 format.

Also the speed differences for PBO differ greatly.
The 1300 MB/s i mentioned above are only achieved with Luminance16. With BGRA i only get 225 MB/s!