In Windows 2000 you cannot use more than 15.8MB of AGP texture memory for DiME cards like all the Matrox cards since the G200, and not more than 31.6 on all DMA cards like all nVidia cards.
However, in an attempt to test the difference between 1x and 2x AGP texturing speed on my pc, I found something very weird:
I tried changing the settings in the 3DMark2000 benchmark in such a way, so that the framebuffer would take up slightly less than 15MB on the G400, forcing it to use as close to the maximum of 15.8MB of AGP textures as possible for the 32MB AGP texture rendering benchmark in 3DMark2000.
When I tested at 1152x864x32 with triple buffering, I got satisfying results, but I wanted to see 3DMark report 'could not perform test' with 32MB textures, just to make sure I pushed the amount of non-local AGP textures to the limit. So I increased the resolution one more notch, and to my surprise, 3DMark just ran the 32MB texture test! I was really surprised, because I thought there wasn't enough texture memory to perform this at that res.
The next step was that I increased the resulution to 1600x1200x32 bit with triple buffer, and guess what? 3DMark ran the 32MB test without the slightest complain! WTF? It also reported that 30MB of the G400 was in use for framebuffer, so that leaves exactly 17MB of RAM including AGP for textures? How can it perform the 32MB test at this res.???
And why can't I run the 64MB test, even at the smallest framebuffer settings?
However, in an attempt to test the difference between 1x and 2x AGP texturing speed on my pc, I found something very weird:
I tried changing the settings in the 3DMark2000 benchmark in such a way, so that the framebuffer would take up slightly less than 15MB on the G400, forcing it to use as close to the maximum of 15.8MB of AGP textures as possible for the 32MB AGP texture rendering benchmark in 3DMark2000.
When I tested at 1152x864x32 with triple buffering, I got satisfying results, but I wanted to see 3DMark report 'could not perform test' with 32MB textures, just to make sure I pushed the amount of non-local AGP textures to the limit. So I increased the resolution one more notch, and to my surprise, 3DMark just ran the 32MB texture test! I was really surprised, because I thought there wasn't enough texture memory to perform this at that res.
The next step was that I increased the resulution to 1600x1200x32 bit with triple buffer, and guess what? 3DMark ran the 32MB test without the slightest complain! WTF? It also reported that 30MB of the G400 was in use for framebuffer, so that leaves exactly 17MB of RAM including AGP for textures? How can it perform the 32MB test at this res.???
And why can't I run the 64MB test, even at the smallest framebuffer settings?
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