GeForce 6800 Ultra problem

[lowinor]

So, I just got my eVGA GeForce 6800 Ultra. And I hook it up, get everything working, reinstall motherboard drives, clean out my old ATI drivers, etc, etc. I run 3dmark03, and get 12484 (this is on a P4 3.2, so this is pretty much what I was expecting out of it).

But I have one problem.

I'm using the card to drive two lcd panels: a Dell 2001FP on my center screen and a Dell 2000FP on my right screen. Both run at 1600x1200.

Now when I have both enabled at 1600x1200, I get a handful of cyan sparklies on the right screen. If I don't have any windows open, there are just a few along the very top of the screen, and if I have a maximized window there's a line thtough the minimize/maximize/close boxes. I've currently got the AT fora maximized on that screen and the lines separating topics on the main list extend to the right of the screen in a faint line of cyan pixels.

This only seems to show up when the right panel is set at 1600x1200. I've swapped around the cables in the back (switching which DVI port each monitor is connected to), and when I do so the pixels show up on the center screen instead. I don't think it's the dvi cable itself as I have previously had the same one connected to a Radeon 7500 PCI with DVI output and had no such problem.

This looks vaguely similar to the problems I used to have on my 9800 Pro with some monitors when I didn't have the 'alternate DVI frequency' option selected, but I'm not finding any such option in the nVidia drivers (and this is the first time I've used a LCD panel at this resolution with nVidia hardware...)

Other relevant system info:
Windows XP Pro SP1
Abit IS7 (Intel i865-ICH5)
Pentium 4 3.20 GHz
2 gigs Corsair value select
480W Antec True 480 power supply
The 6800 is idling at 58C (and reporting a 41C ambient temp)
I've got a Radeon 7500 PCI sitting in the system, currently disabled via Device Manager
Chaintech sound card using the Envy24 chip
Using onboard LAN (onboard sound disabled)
Three hard drives (Raptor 36, Raptor 74, WD 80 Gig IDE)
No optical drives or floppy


I've RMAed cards in the past with similar problems (cyan/magenta pixels showing up onscreen) attributing it to bad ram on the card, but these pixels only show up on one screen and at one resolution and don't appear to be associated with any stability problems (as I've had zero stability problems with the card so far). I'm currently guessing it's an issue with the DVI signal output by the secondary port, but am otherwise stumped (and have no idea how to fix it).

I've submitted a question to eVGA tech support, but honestly, I have more faith in this forum.

Thanks in advance for any help!

 

[DoughKey]

Have you tried only connecting a display to that port and disabling the other one? Just as test to narrow things down?

Not that this necessarily has anything to do with your problem but you might find it interesting.

-D

 

[lowinor]

Thanks for the response.

I think I've fixed it, and so far (in what may be more amazing) it's keeping the settings.

By getting rid of the front porch and back porch under "Advanced Timing" under "Change Resolution". As far as I know, that's what the "reduce DVI frequency" option for ATI drivers does, and it solved the problem.

Notably, killing the porches put the signal to 130 MHz (from 162 MHz for the 'standard' 1600x1200 60 Hz signal).

My suspicion is that the card has a full 165 MHz TDMS transmitter for the first head and only a 135 MHz transmitter for the second head; that would, at least, explain why dropping the signal to 130 MHz fixed my problem.

Oh, nevermind. it just showed back up while typing this, at a 130 MHz bandwidth resolution. Back to hacking. Hoping the card isn't defective

 

[lowinor]

Hrm.

Ok, I'm getting some results fiddling with the settings, but I have to admit I'm lost at this point. I've gotten rid of most of the issues, but they keep showing up (albeit in increasingly unusual circumstances -- currently the culprit is horizontal T-junctions -- I'm getting the pixels where the horizontal line would continue if not interupted.

Really hoping someone can tell me what exactly it is I'm fooling with when I change settings under the Advancing Timing dialog

 

[Johnbear007]

Originally posted by: lowinor
Hrm.

Ok, I'm getting some results fiddling with the settings, but I have to admit I'm lost at this point. I've gotten rid of most of the issues, but they keep showing up (albeit in increasingly unusual circumstances -- currently the culprit is horizontal T-junctions -- I'm getting the pixels where the horizontal line would continue if not interupted.

Really hoping someone can tell me what exactly it is I'm fooling with when I change settings under the Advancing Timing dialog

You should send an e-mail to nvidia.

 

[Marsumane]

Originally posted by: DoughKey
Have you tried only connecting a display to that port and disabling the other one? Just as test to narrow things down?

Not that this necessarily has anything to do with your problem but you might find it interesting.

-D

So wait a minute. Did u do this suggestion or not yet? If its any of the problems that u suspect, i dont see why using only one monitor wouldnt reproduce these effects.