6800 Ultra will not work in any AGP 8x Mobo

[eBauer]

Basically the other day I turned on my second system (Lanparty 250gb, Prolink 6800 Ultra) and it would not post. Swapped the 6800 in another system, same result. Swapped it in a third system, worked like a charm.

What I figured out was that it will post / run just fine in any AGP 4x motherboard. (Intel 845 and older, KT333 and older) However it will not work in any AGP 8x motherboard.

Any ideas?

 

[Wolfshanze]

I find it hard to believe it's an AGP 8x/4x thing.

You can toggle the AGP from 8x to 4x in most MB BIOS screens. Have you tried running the 6800U in one of the "troublesome AGP 8x" MBs while running the MB in 4x mode?

I would highly suggest going into one of the AGP 8x MBs, changing the AGP port to 4x, then trying the 6800U in it while the MB is in 4x mode... this should confirm or rule-out if it's really a 8x/4x problem or something else all-together.

I have a sneaking suspicion the 4x/8x factor is not the problem (but the above test would tell you if it is or not).

 

[Brian48]

I had this exact same problem with my old 6800GT. It was completely unstable with my Soltek SL-K8TPro-939. At first I thought it was the card, but then I tried a X800XT PE, 9800Pro, and 9700Pro in the same system and it did the same thing. Finally figured out that the motherboard has an issue with 8x AGP. Set it to 4x AGP in the BIOS and it was completely stable after that regardless of what video card was installed.

In regards to performance loss going from 8x to 4x, I did not see any significant decreases. With the various benchmarks I threw at it, the dip in fps was so miniscule, it was irrelevant. Very often, future driver updates made up the difference.

 

[Steelski]

could be a fast wright issue. make sure that is off.

 

[eBauer]

Originally posted by: Wolfshanze
I find it hard to believe it's an AGP 8x/4x thing.

You can toggle the AGP from 8x to 4x in most MB BIOS screens. Have you tried running the 6800U in one of the "troublesome AGP 8x" MBs while running the MB in 4x mode?

I would highly suggest going into one of the AGP 8x MBs, changing the AGP port to 4x, then trying the 6800U in it while the MB is in 4x mode... this should confirm or rule-out if it's really a 8x/4x problem or something else all-together.

I have a sneaking suspicion the 4x/8x factor is not the problem (but the above test would tell you if it is or not).

Already tried changing it to 4x in the bios, along with disabling fast writes.

 

[Brian48]

Originally posted by: eBauer
Already tried changing it to 4x in the bios, along with disabling fast writes.

Yeah, but you might still have to force it to run at 4x AGP under software. Disabling it under the BIOS simply makes it unavailable, but that doesn't stop the drivers from making the attempt. You might want to install one of those 3rd party tweaking utilities to check if you're actually at 4x AGP.

 

[eBauer]

Originally posted by: Brian48

Originally posted by: eBauer
Already tried changing it to 4x in the bios, along with disabling fast writes.

Yeah, but you might still have to force it to run at 4x AGP under software. Disabling it under the BIOS simply makes it unavailable, but that doesn't stop the drivers from making the attempt. You might want to install one of those 3rd party tweaking utilities to check if you're actually at 4x AGP.

Any system with a AGP 8x board refuses to even post with the 6800u, so how would I force it to run at 4x AGP under software?

Is there a way to force AGP 2x/4x in the video card's bios?