Weird Doom 3 image jump

[Jimstep]

I know this topic has been discussed before, but I'm really stumped on how to eliminate this jump effect I am seeing. Doom 3 game play is good with fluid mouse movement. But I noticed that when I strafe sideways, there is a slight jump in the image about every 2 to 3 seconds of movement. Once I noticed the image jump while strafing, I now notice it while walking forward or any type of movement other than rotating the image with the mouse. It is more pronounced if I turn AntiAliasing on. Other than that, It doesn't matter what image size I'm running (ie. 640x480 compared to 1280x1024), or what the image quality setting is (ie. low vs ultra). I've tried four different nVidia drivers, the most current being version 77.72. Vsync settings don't effect it.

My system is:
MSI K8N Neo2 (v1.9 bios)
NVIDIA nForce3 System Driver 5.03
AMD 64 3700+ San Diego
2 Corsair TwinX512-3200XL (timings 2-2-2-5) using dual channel at 1T
nVidia Geforce 6800 GT (NV40GT) 256Mb (77.72 drivers)
Maxtor 120Gb SATA wiht 8Mb cache
Windows XP (SP2)

Doom3 with 1.3.1302 patch

Timed demo frame rate ranges from 75 to 108 depending on image setting in the game, like AA, AF, Vsync and image size.

I've tried every setting in different tweak guides I have found on the internet. No matter what I do, I still see this image jump.

Does anyone else see this? Is there a way to eliminate it?

[MadPistol]

make sure that you don't have driver level vsync enabled. traditionally when I do this with doom 3, it causes the "jump" you are talking about. It's basically the processor catching up with the video card, as the video card is a limiting factor on this game.

I'm not sure there is a way to eliminate this other than to just make sure that vsync is off on all lvls. That's about all I can tell ya. :t

[Jimstep]

The vsync turned off makes it less noticeable. Thanks for the tip. I have the AGP 8x video card. I wonder if the pci-express version has enough bandwidth to further reduce the lag time?

[MadPistol]

No. PCI-express is still limited by the bandwidth of the card. Same for AGP. It's a shame really that they didn't fully realize the power of AGP before replacing it. :t