NVIDIA's AGP versus the kernel's AGPGART?

Question

I've just taken the time to figure out how to use nvidia-agp instead of the kernel's agpgart, but it doesn't give any difference in performance (at least based on <code>glxgears</code> results).  Is there any point to switching?
To get it to work, I had to blacklist <code>agpgart</code> in my rc.conf file, and then add this line to the device section of my xorg.conf file:
Option "NvAgp" "1"
which gives me what I was looking for:
$ cat /proc/driver/nvidia/agp/status
Status: Enabled
Driver: NVIDIA
AGP Rate: 8x
Fast Writes: Disabled
SBA: Enabled
Does anyone have any experience with these, or did I just waste my time?  Either way I get just about 1700fps using glxgears with a GeForce 6200.

Answer 1

Does somebody knows if those settings are suitable at any point for a nVidia pci-express graphic card ?
Here are some output I get with a GeForce 6200TC PCIe.
$ lsmod | grep agp
amd64_agp              11140  1
agpgart                31368  2 nvidia,amd64_agp
$ ls /proc/driver/nvidia/
cards/    registry  version   warnings/
$ cat /proc/driver/nvidia/cards/0
Model:          GeForce 6200 TurboCache(TM)
IRQ:            10
Video BIOS:      05.44.02.11.00
Card Type:      PCI-E
$ cat /proc/driver/nvidia/registry
VideoMemoryTypeOverride: 1
EnableVia4x: 0
EnableALiAGP: 0
NvAGP: 3
ReqAGPRate: 15
EnableAGPSBA: 0
EnableAGPFW: 0
SoftEDIDs: 1
Mobile: [phone]
ResmanDebugLevel: 4294967295
FlatPanelMode: 0
DevicesConnected: 0
VideoEnhancement: 0
RmLogonRC: 1
VbiosFromROM: 0
ModifyDeviceFiles: 1
DeviceFileUID: 0
DeviceFileGID: 0
DeviceFileMode: 438
RemapLimit: 0
UseCPA: 4294967295
DetectPrimaryVga: 0
/etc/X11/xorg.conf :
Section "Screen"
        Identifier      "NV Monitor"
        Device          "NV 6200TC"
        Monitor         "ViewSonic E92f+"
        Option          "DPMS"
        Option          "NoDDC"          "false"
        Option          "NoLogo"         "true"
        #Option         "Coolbits"       "true"  (WW) NVIDIA(0): Option "Coolbits" requires an integer value
        #Option         "UseEditDPI"     "true"  (WW) NVIDIA(0): Option "UseEditDPI" is not used
        #Option         "UseEditFreqs"   "true"  (WW) NVIDIA(0): Option "UseEditFreqs" is not used
        Option          "NvAGP"          "1"
        Option         "UseEdidFreqs"    "1"
        #Option         "EnablePageFlip"         "true" (WW) NVIDIA(0): Option "EnablePageFlip" is not used
        Option         "NoBandWidthTest" "1"
        Option         "DigitalVibrance" "3"
        Option          "RenderAccel"    "true"
        Option         "backingstore"    "true"
        #should be switched off *if* the system crash:
        Option          "RenderAccel"    "true"
        Option          "AllowGLXWithComposite" "true"