IQ - 2 head vs 3 stretch?

[HaloFX]

Is there any quality loss when moving from 2 head independent to 3 screen stretch? I know there will be a slight slow down, but what about quality?

[edit]
I am looking over the Matrox site and under the 2 head stuff it mentions 2 RAMDACs. Then on the Triple head it says "a specialized third RAMDAC". Does this mean in triple the other 2 are not used? so the IQ could be different?

[HaloFX]

Nobody has compared the image quality between 2 head independent and 3 head stretch??

[Cobos]

I don't know anything about any possible IQ difference since I neither have a Perhelia nor a 3 monitor setup
What I do know (I'm 99% sure this is right) is that the Parhelia chip has 2 400Mhz ramdacs embedded in the chip that drives the 2 first heads, while if you power up the third head it uses the extra ramdac you mentioned.

Cobos

[HaloFX]

This is part of the reason I am trying to determine if they look different. I was unable to tell if the third RAMDAC was used in conjunction of the first two, or if the third was used INSTEAD of the the other two. I tend to believe that it is used instead of the others. Which is why three head is stretch only. If it was all three I would think we would have three head independent, with the third head just not performing as well; kinda like the G400. The second head on the g400 used a slower RAMDAC.

So if this is the case, one RAMDAC for all three displays, then the quality of the three head stretch could be different from the two head independent.

[Kruzin]

RAMDAC had nothing to do with the speed the card runs at, just the resolution/refresh rate it's capable of on that head.

Cobos is correct. The third RAMDAC is only used for the 3rd display, with the 2 main RAMDACs always running the first 2 displays.

I have seen no loss in visual quality on the primary or secondary display going from dualhead to triplehead.

[HaloFX]

Excellent! Thank you!

[bibble]

Kruzin,

I was really interested in P until I found that three head was stretch only. Is there ANY WAY that in software the third could be an independant resolution or do we have to wait for a hardware refresh?

[az]

The latter. But maybe there will be an app which enables three desktops through one viewport, thus enabling you to have three independent desktops, which just happen to have the same res and color depth. I think PowerDesk HF does part of this now.

BTW, how is the third display's image quality?

AZ