eyefinity setup issue, dvi->vga, dvi, DP->dvi

[chobint]

Ok, so I've got my eyefinity setup like this:
dvi -> vga
dvi
dp -> dvi

Since I'm drawing two digital signals and one analog, this seems like it should work, but it doesn't. It only allows two monitors to be enabled at any given time. I imagine this has something to do with the 2 digital clock limitation.

Can anyone give some incite as to why this is not working? Is it because even when drawing the analog signal from the dvi-i port, the card is using one of the digital clocks to generate the digital portion of the dvi-i, even though it's not in use?

 

[noquarter]

Ok, so I've got my eyefinity setup like this:
dvi -> vga
dvi
dp -> dvi

Since I'm drawing two digital signals and one analog, this seems like it should work, but it doesn't. It only allows two monitors to be enabled at any given time. I imagine this has something to do with the 2 digital clock limitation.

Can anyone give some incite as to why this is not working? Is it because even when drawing the analog signal from the dvi-i port, the card is using one of the digital clocks to generate the digital portion of the dvi-i, even though it's not in use?

Pulling off the dvi port to do VGA still takes up a clock generator which provides the clock signal for RAMDAC/TDMS output. VGA, HDMI, DVI all require a clock signal to sync up the display, and the GPU only provides 2 of these signals, DP does not require a clock signal. So even though you're mixing analog and digital it still uses up the same limited resource.

An active DP->DVI adapter has a chip in it to generate an additional clock signal, a passive one does not and relies on the GPU to provide the clock signal. A DP->VGA converter has a chip in it but is not 100% reliable and can cause screen blanking, but is only $30.

 

[ClearM4]

Get an DP-to-VGA adaptor (this is actually an active adapter). DP-to-DVI requires an active adapter.

Following wil work:

DVI
DVI
DP -> VGA

 

[hbidad]

consider this ... http://www.amazon.com/Accell-UltraA...1?ie=UTF8&s=electronics&qid=1260294111&sr=8-1

I looked around the web to find less complaints about this one. It's the one I got and only once did I every have a problem so far. Some reason it would not wake up after being hibernated. I unplugged it and plugged it back in and all was well. No other problems, no screen flickering. Then again I leave my pc on for weeks on end.

 

[chobint]

Pulling off the dvi port to do VGA still takes up a clock generator which provides the clock signal for RAMDAC/TDMS output. VGA, HDMI, DVI all require a clock signal to sync up the display, and the GPU only provides 2 of these signals, DP does not require a clock signal. So even though you're mixing analog and digital it still uses up the same limited resource.

An active DP->DVI adapter has a chip in it to generate an additional clock signal, a passive one does not and relies on the GPU to provide the clock signal. A DP->VGA converter has a chip in it but is not 100% reliable and can cause screen blanking, but is only $30.

Get an DP-to-VGA adaptor...

consider this ... <link>

Thanks for the clarification noquarter, that is what I expected was happening. Looks like DP->VGA will be my next try, once it arrives in the mail.

It's really too bad ATI had to make eyefinity such a PITA with displayport and limited clocks. It almost completely deterred me from making an eyefinity setup at all.

 

[noquarter]

Thanks for the clarification noquarter, that is what I expected was happening. Looks like DP->VGA will be my next try, once it arrives in the mail.

It's really too bad ATI had to make eyefinity such a PITA with displayport and limited clocks. It almost completely deterred me from making an eyefinity setup at all.

Totally worth it in the end though Besides I actually hope DisplayPort takes off, it's a much cooler spec than HDMI/DVI, and royalty free