For FX series NVIDIA cards and older, I tend to use FW71.89 in XP. Works really well.

That chipset isn't the greatest though. You can try installing the chipset driver (version 1.21 is the latest one I believe). I'd be highly surprised if the BIOS had any options to change the AGP settings, but if it does I'd play around with those too, mainly Fastwrites and the speed setting.

Hmm didn't work, it does install fine, but the same problems appear, in OpenGL is broken, misaligned or corrupted textures or polygons sometimes, in DirectX everything is broken.

I've uploaded screenshots to this folder in Drive: https://goo.gl/V5NsKZ (these are in OpenGL, In DirectX sometimes Half Life crashes, the other game is the Cube engine)

Something that comes to my mind is the factory overclock, that makes the AGP bus to be a little bit faster than expected, i've tried several videocards, 3 of them fail:

GF4 MX4000
Savage4
3DImage 9750

The others work fine:

GF2 MX400
SiS 315
Rage Pro Turbo

In some days i'm expecting to get a cheap FX 5200 to test and for other pc.

Now I will try SetFSB to see if I can lower the FSB from 105 to 100.

edit: Nop it didn't work, it does set the frequency correctly, but the broken graphics remain, so I will dump this old cheap mobo and will use something better. Thanks.

That is some suspiciously low compatibility.
Did you set AGP 4x in setup? Or fiddle with other AGP settings.

That's the big problem here, it has NO adjustment for anything, it's PCChips and comes factory-oveclocked and with the processor soldered, in the bios setup there's nothing that affects performance or compatibility.

I have at least 3 mobo for socket 478, but the heatsink attachment is broken in all of these, also don't have enough DDR memory modules.

That is a bummer. There are still software tools to switch some sensitive features. Powerstrip, Rivatuner etc.

Well, i've tested with powerstrip, the graphical glitches doesn't dissapear and GPU-Z doesn't detect any change to AGP4x, also, in forceware with the Coolbits.reg doesn't detect AGP4x or any other option to be supported by the mobo.

Later, i've tested an FX 5200 from XFX, like the GF4, and even the board is the same in both, but the FX 5200 works pretty good, even with overclock. So that just makes me wonder if there is any incompatibility on the NV chip that makes those glitches appear, some incompatibility that can't be solved but in hardware.

this sounds a lot like the m810lmr, there are good compatibility guides that might work for your board too
I think the sis 730s onboard is much cooler than the mx4000 😀

Not exactly, the onboard video (sis 300) has performance up to savage4-level, so it isn't an option. The mx4000, even with it's anemic 32 bit memory bus, outperforms it by a really big margin, especially when directx 7 (T&L) is used.