IIRC the P3B-F is a AGP 1x board, not sure if it supported 2x on early revisions, what revision is your board ?>

Revision 4

I'm sorry how can it be the P3B-F be an agp x1 motherboard? The 440bx supports agp up to 2x, how can the motherboard dictate to be agp 1x?
From the manual of the Asus P3B-F:

AGP Slot: Supports an Accelerated Graphics Port card for high performance,
component level interconnect targeted at 3D graphical display applications using a 1X or 2X mode bus

Is the bios updated to the latest version?

Nemo1985 wrote on 2024-05-12, 04:32:

I'm sorry how can it be the P3B-F be an agp x1 motherboard? The 440bx supports agp up to 2x, how can the motherboard dictate to […]
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I'm sorry how can it be the P3B-F be an agp x1 motherboard? The 440bx supports agp up to 2x, how can the motherboard dictate to be agp 1x?
From the manual of the Asus P3B-F:

AGP Slot: Supports an Accelerated Graphics Port card for high performance,
component level interconnect targeted at 3D graphical display applications using a 1X or 2X mode bus

Is the bios updated to the latest version?

Not at all odd actually, they claim 2x compatibility not that it will actually work with every 2x AGP card out there. In fact there were a large number of BX boards that claimed AGP 2x and were never able to actually run at that speed or could run at that speed but didn't implement the whole standard and as such had numerous compatibility issues. Also not uncommon was having AGP 1x/2x cards were also picky about which AGP2x board they would work in at that speed or even post. I even own one such card that is infamous for being a picky bitch to get running, its fully AGP 2x compatible but will really only work in a few boards that implement AGP 2x fully and correctly.

I honestly dont care what the manual says either, manual errata was also common back then too along with using a manual from a different revision/model of a board and then claiming support for features the fabs knew were never on that revision of the board.

The P3B-F has a IO voltage jumper on the motherboard to set the AGP voltage, ASUS has it at 3.5v default but you can change the jumper to have it at 3.65v perhaps this jumper can help here or perhaps its already set to 3.65v and should be set back to 3.5v.

Or the G200 simply isn't compatible with how AGP 2x is setup on this board.

Could it be that bus speeds are set higher than 66 and the AGP/FSB relation is set wrong, making AGP run too fast?

Set Dip switch 6 to OFF (default) to run AGP at 2/3 of fsb. With ON it runs 1:1, which is too fast at 100 MHz FSB.

Either the AGP divider isn't set to 2/3 or the video card driver is bugged. It would be weird if a late Intel 440BX-based motherboard such the ASUS P3B-F wasn't able to fully support AGP 2x.

Amen, Intel was the developer of the agp protocol, their motherboard never suffered for flaky agp integration, Intel also developed the Intel 740 back in time just to show the advantage of the agp over pci.