There was an RLowe patch for Nvidia video cards that use memory banking and >512MB VRAM.

I wonder if the same fix would work here.

R. Loew has a patch for that: https://archive.org/details/PTCHNVSZ

Edit: I just realized his patch is only for Nvidia cards.

I haven't checked this patch for Nvidia cards but it seems to me that it won't work because it modifies the Nvidia driver settings, not the system.

You can't "decrease" VRAM capacity by changing software settings.
It needs a vBIOS mod, and swapping vBIOS also won't help because 512MB card uses different memory timings than 256MB ones. Either way, good luck trying to swap timing tables for memory (if you are willing to go that far).

In short : You can try to limit AGP aperture size to minimum (which determines how much RAM is allocated to GPU), but it may not help in this case.
Also, there is REALLY no point in having 512MB memory on Win98, neither games nor programs can ever use this much under Windows 98 (OR they can be run on WinXP).

PS. Another option is to release as much RAM as possible from other drivers by disabling them), which may help if cause of this issue is memory conflict (drivers from two devices get assigned the same adress space in RAM). I assume here, that it's memory conflict, and not fundamental incompatibility of Windows 98 with 512MB ATI cards.

I can't change the AGP aperture size because it's a PCI-E card. Windows doesn't detect any memory conflicts either. I know Win9x doesn't need 512MB of graphics memory, but this card came up for auction so I bought it. If I had a choice, I'd take the 256MB version. 😉

Sorry... I missed that (PCIe card).

It's device manager that informs you of issues with hardware.
If it's fine (no yellow marks anywhere), it shouldn't show a settings/hardware error ?
Q : Can you change desktop resolution (or bit depth) ?

agent_x007 wrote on 2023-07-27, 08:23:

Sorry... I missed that (PCIe card). […]
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Sorry... I missed that (PCIe card).

It's device manager that informs you of issues with hardware.
If it's fine (no yellow marks anywhere), it shouldn't show a settings/hardware error ?
Q : Can you change desktop resolution (or bit depth) ?

There are no conflicts and I can't change the resolution.

If there is patch for Nvidia 512MB cards that work, then somehow it is possible to patch ATi cards also?
I luckly have 2x800XL 256MB PCIE cards, one with extra connector, other without, latest drivers work.

I bet that the driver cannot handle more than 256mb of ram. Without a patch or some configuration change, I'm sure I won't be able to run this card under Win9x. The worst thing is that under Win9x this card would be God but under Windows XP it's just weak or average at best.