Hello

I have:
AMD Athlon 64 3200+ 2000 MHz
Gigabyte GA-K8NS-939 nForce 3 Ultra (with AGP port)
RAM: 1536 MB
Leadtek WinFast A6600 GT TDH (GeForce 6600 GT 128 MB)

Before I have Fedora Core 4 i386 (2.6.15-1.1833_FC4) and everything was OK (doom3 work OK)

Now I installed Fedora Core 5 x86_64 Re-Spin 20060523 (2.6.16-1.2122_FC5)
I installed nvidia drivers (from livna.org), but doesn't work OpenGL, and everything with graphics is working slow (drawing windows, etc.)

Doom3 doesn't run:
WARNING: vertex array range in virtual memory (SLOW)
signal caught: Segmentation fault
si_code 1

I guess that it is problem with AGP Aperture
dmesg:
Aperture from AGP @ e0000000 size 4096 MB (APSIZE 0)
Aperture from AGP bridge too small (0 MB)
agpgart: Detected AGP bridge 0
agpgart: Aperture conflicts with PCI mapping.
agpgart: Aperture from AGP @ e0000000 size 4096 MB
agpgart: Aperture too small (0 MB)
agpgart: No usable aperture found.
agpgart: Consider rebooting with iommu=memaper=2 to get a good aperture.
NVRM: loading NVIDIA Linux x86_64 Kernel Module 1.0-8762 Mon May 15 13:58:14 PDT 2006
NVRM: not using NVAGP, kernel was compiled with GART_IOMMU support!!

How to repair it?

Solution: Ctrl+F1 in BIOS...

In manual of motherboard there is no information about what is in this menu.
But yes... there is a small mention about Ctrl+F1...

There is many people with similar problem, so I was thinking that it is a serious problem. I compiled kernel without agpgart and IOMMU support (to run NvAGP), but before install it, I found that there is hidden menu in BIOS

Why Gigabyte sets default AGP Aperture only to 32MB and hide it in BIOS?!?
I set AGP Aperture to 512MB. Maybe too many?

About Doom3 in FC5 x86_64:
To run this game (and perhaps Quake4) you need do:
yum install xorg-x11-drv-nvidia-libs-32bit (from livna.org repository)
yum remove mesa-libGL.i386

PS. Sorry for my English - my native language is Polish...