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512MB nVidia Graphics Cards


rloew
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512MB Graphics Cards have proven to be problematical when used with Windows 9x.

I ran some tests with a nVidia 7200GS and a nVidia 7950GT on various Motherboards to determine why.

Apparently nVidia decided to change their design approach after releasing some 512MB Cards.

Previously they provided access to the entire Video RAM through the Memory Mapped I/O Space.

This approach unfortunately limits the amount of System RAM that can be used by 32-Bit OSes.

With the later 512MB Cards they decided to Bank Memory access through a smaller MMIO Space, typically 256MB.

Starting with the 8xxx series they also implemented a Memory Page Mapper similar to the MMU in the CPU.

The 7200GS is an example of the earlier design. The 7950GT is an example of the later one.

The 82.69 nVidia Driver does not recognize the difference between the reported amount of Video RAM and the size of the MMIO Space allocated to the Card.

The Driver overwrites the MMIO Space above the Video Card's allocation.

Depending upon what is in the next 256MB of MMIO Space, your Computer can crash or other Devices, such as USB, can malfunction.

A few people have been lucky enough not to have anything important in this space so they have been able to use a 7950GT although they only get 256MB.

Others have not been so lucky.

I have developed two solutions for this problem.

1. A Patch to the 82.69 Driver to make it recognize the smaller MMIO Space.

2. A BIOS Patcher for the nVidia BIOS ROM to increase the amount of MMIO Space it claims.

The first is more universal but limits the Video RAM typically to 256MB. The second provides the full 512MB Video RAM of the Card.

I am preparing a Package to put on my Website.

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  • 2 weeks later...

I have developed two solutions for this problem.

1. A Patch to the 82.69 Driver to make it recognize the smaller MMIO Space.

2. A BIOS Patcher for the nVidia BIOS ROM to increase the amount of MMIO Space it claims.

The first is more universal but limits the Video RAM typically to 256MB. The second provides the full 512MB Video RAM of the Card.

I am preparing a Package to put on my Website.

Me Like + 1 (hell, just NOW i saw the simple like button...)

Edited by ragnargd
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Really great! Congrats rloew!

Does that means we can use nvdia cards generation 8XXX and later? I ask because 7XXX cards are getting really hard to find in my country at least but nvidia 4xx and later are in good supply.

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I'm afraid not.

8xxx and later cards use significantly different interfaces than the earlier ones.

My Patches are mainly for 6xxx and 7xxx 512MB Cards.

At this point I don't think there are any compatable cards available at my local retailers at all.

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I'm afraid not.

8xxx and later cards use significantly different interfaces than the earlier ones.

My Patches are mainly for 6xxx and 7xxx 512MB Cards.

At this point I don't think there are any compatable cards available at my local retailers at all.

 

For me, the patch for the OS would be enough, as when 98 was hip, everybody knew its limitations, and made no software that deliberately used that amount of Video RAM. And furthermore, this version is without risk for multi-boot-systems, as it does not touch other operating systems in any way.

 

Still, regarding the VGA-Bios-patch, what effect can be expected on Windows XP or Windows 10? Did you already test such constellations?

 

Cheers, Ragnar G.D.

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The Patch is ready. I plan to update my website over the weekend.

There will be a free test program that you can use to test your system before purchase.

I haven't tested the BIOS Patch in XP as I have yet to put the one problematic card (7950GT) in a system with XP.

I only have Windows 10 in a Laptop, so I cannot test that at this time.

I did a BIOS Patch on a 256MB PCI 6200GS that claimed 512MB, the reverse of the 7950GT, and it works in XP.

The main impact on Windows XP would be the maximum amount of 32-Bit RAM available.

64-Bit systems would be unaffected as the Memory is not lost but hoisted up into the 64-Bit space.

Incidentally, the main Patch is for the nVidia Driver not the OS. I do include an OS Patch that fixes a separate problem that I have seen in some Intel branded Motherboards.

Edited by rloew
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The Patch is ready. I plan to update my website over the weekend.

There will be a free test program that you can use to test your system before purchase.

I haven't tested the BIOS Patch in XP as I have yet to put the one problematic card (7950GT) in a system with XP.

I only have Windows 10 in a Laptop, so I cannot test that at this time.

I did a BIOS Patch on a 256MB PCI 6200GS that claimed 512MB, the reverse of the 7950GT, and it works in XP.

The main impact on Windows XP would be the maximum amount of 32-Bit RAM available.

64-Bit systems would be unaffected as the Memory is not lost but hoisted up into the 64-Bit space.

Incidentally, the main Patch is for the nVidia Driver not the OS. I do include an OS Patch that fixes a separate problem that I have seen in some Intel branded Motherboards.

 

I'll test this thoroughly happily, once you're done.

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  • 4 months later...

You have the 7950GX2. It reports two separate PCI Devices, one for each board.

The Secondary Card returns a Class Code not recognized by the Program so it doesn't report any information on it.

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