Remove all power and try resetting the cmos on the MB with the ATi card installed.

Are you using the same monitor when testing on both motherboards ?

Horun wrote on 2020-02-29, 02:58:

Are you using the same monitor when testing on both motherboards ?

Yes. Tried both DVI ports and a VGA adapter on both ports and two different monitors (both older LCDs). Same monitors work fine with the 6800GT in the nForce 3 or with the HD3850 in the nForce 2.

Ozzuneoj wrote on 2020-02-29, 03:08:

Horun wrote on 2020-02-29, 02:58:

Are you using the same monitor when testing on both motherboards ?

Yes. Tried both DVI ports and a VGA adapter on both ports and two different monitors (both older LCDs). Same monitors work fine with the 6800GT in the nForce 3 or with the HD3850 in the nForce 2.

If you reset the BIOS as texterted mentioned then that sort of leaves the board bios as the problem. If it was full incompatibilty then you would get beeps like no vid card but since it does not then the board BIOS see's the video bios but does not initialize it properly. Have a PCI vid card that some boards don't like and get just a black screen but on others it works just fine. I chock it up to how the board bios and that specific vid bios work together. Is there a video bios update for the video card ? Just a thought....

texterted wrote on 2020-02-28, 23:37:

Remove all power and try resetting the cmos on the MB with the ATi card installed.

Welp, I tried this once after you mentioned it and it did reset the CMOS but nothing changed. I then went into the BIOS using the 6800GT, reset the system to fail safe defaults (which didn't seem to change any AGP related settings... since I had just reset the CMOS) and then changed the AGP aperture to 512MB, just to try it, then I shut down and put the HD3850 back in for the 30th time and... it works! So, I thought it was the AGP aperture, so I set it back to 128MB (the default), and... it still works! So, I have no idea what was set incorrectly, or if it was a BIOS bug (this is a beta BIOS), but it seems to be working after resetting to failsafe defaults even though I can find no settings that actually changed. Changing to optimized defaults still works as well. It's a mystery! 😄

Thanks for the help guys.

Now I have to figure out what on earth to do with this computer. I'm thinking it'd be a decent candidate for an overkill Windows 98SE + XP system, since there apparently isn't any way to get nForce AGP drivers working with ATI cards in Vista or newer. Then again, I was planning to do the same thing with my totally overkill i5 2500K system too now that I've finally upgraded. Either one would require a PCI video card for 98SE. I recently got an Audigy 2ZS with the front panel which would be a pretty neat addition to either system.

To be honest, I just hate getting rid of PCs I've had for years... the only ones I still use frequently are the ones I use for testing old parts. I could probably build 15 period-correct systems to cover the last 25 years of gaming, and yet I never have time to actually play any games. 😆

EDIT: One question about the Audigy 2ZS front panel... what is with the mini-din-style MIDI connectors? Is this a standard cable or some "Creative" engineering from Creative that requires an impossible to find cable or adapter? It is 5-pin with a notch, so a male PS/2 to AT\DIN adapter won't work, unless you remove one of the pins from the PS/2 end, but I have no idea if these would be wired correctly.

Result! 😀

I've seen similar with bridge chip AGP cards. I think the card shuts down before the board detects it as AGP 8x and applies the correct voltage.