rule of thumb regarding video cards and monitors

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husky86

We have an ATI Radeon HD 3650 PCle x16 video card in an HP desktop. The back
of the video card has 3 ports: 1 DVI and 2 DisplayPort.

We would like to have 3 monitors hooked up to this desktop. When we
contacted HP support about this desire, we were assured that 3 monitors could
be connected directly to the video card WITHOUT the need to split to
connection with a special adapter.

However, when we connect 3 flat-panel monitors to this video card—directly
to the 3 ports—only 2 monitors function at any given time.

This is also true when we try other hookup scenarios, like using the 2
DisplayPort ports and splitting one of the connections to 2 monitors.

We are assuming therefore that the general rule with any video card is that
is can only be used to 2 monitors at any given time?

Is this correct?
 
Sorry about this questions howing up twice; I got an error message the first
time I tried to post. It looks like it went through, however.
 
Not sure about your Radeon, but many cards that support
only two monitors have additional connector for one of the outputs
(like VGA and HDMI).
There are special cards that supoort 8 and more monitors.

-- pa
 
husky86 said:
We have an ATI Radeon HD 3650 PCle x16 video card in an HP desktop. The back
of the video card has 3 ports: 1 DVI and 2 DisplayPort.

We would like to have 3 monitors hooked up to this desktop. When we
contacted HP support about this desire, we were assured that 3 monitors could
be connected directly to the video card WITHOUT the need to split to
connection with a special adapter.

However, when we connect 3 flat-panel monitors to this video card—directly
to the 3 ports—only 2 monitors function at any given time.

This is also true when we try other hookup scenarios, like using the 2
DisplayPort ports and splitting one of the connections to 2 monitors.

We are assuming therefore that the general rule with any video card is that
is can only be used to 2 monitors at any given time?

Is this correct?
Click to expand...

Typical rule of thumb

"Any two of three connectors can be used"

For a diagram, see PDF page 8 here. Wait a few moments, until
Acrobat renders the "AVIVO Display Engine" diagram. The
diagram shows there are two display pipelines, which is
why there is a two display at a time limitation on a
single GPU chip. The output crossbar concept, allows
the display pipelines to be connected to particular outputs.

http://ati.amd.com/products/radeonx1k/whitepapers/X1000_Family_Technology_Overview_Whitepaper.pdf

To drive more displays, you need more GPU chips. There
are some cards with two GPU chips and four display
connectors. This one is a quad VGA. With the right
adapter cables, it might also be possible to do quad DVI
with it.

http://images17.newegg.com/is/image/newegg/14-139-037-S06?$S640W$

Here is another one, but this one, relatively speaking,
will draw a lot more power from the power supply.

SAPPHIRE 100260SR Radeon HD 4850 X2
http://www.newegg.com/Product/Product.aspx?Item=N82E16814102813

It needs only one PCI Express x16 slot, but is a
wide card and needs plenty of room for cooling.

http://images17.newegg.com/is/image/newegg/14-102-813-S01?$S640W$

For a power estimate on the HD 4850 X2 (225.1 Watts in 3D mode), see

http://www.xbitlabs.com/articles/video/display/sapphire-hd4850x2_8.html#sect0

HTH,
Paul
 
Thanks for this info!

Paul said:
Typical rule of thumb

"Any two of three connectors can be used"

For a diagram, see PDF page 8 here. Wait a few moments, until
Acrobat renders the "AVIVO Display Engine" diagram. The
diagram shows there are two display pipelines, which is
why there is a two display at a time limitation on a
single GPU chip. The output crossbar concept, allows
the display pipelines to be connected to particular outputs.

http://ati.amd.com/products/radeonx1k/whitepapers/X1000_Family_Technology_Overview_Whitepaper.pdf

To drive more displays, you need more GPU chips. There
are some cards with two GPU chips and four display
connectors. This one is a quad VGA. With the right
adapter cables, it might also be possible to do quad DVI
with it.

http://images17.newegg.com/is/image/newegg/14-139-037-S06?$S640W$

Here is another one, but this one, relatively speaking,
will draw a lot more power from the power supply.

SAPPHIRE 100260SR Radeon HD 4850 X2
http://www.newegg.com/Product/Product.aspx?Item=N82E16814102813

It needs only one PCI Express x16 slot, but is a
wide card and needs plenty of room for cooling.

http://images17.newegg.com/is/image/newegg/14-102-813-S01?$S640W$

For a power estimate on the HD 4850 X2 (225.1 Watts in 3D mode), see

http://www.xbitlabs.com/articles/video/display/sapphire-hd4850x2_8.html#sect0

HTH,
Paul
Click to expand...
 
husky86 said:
We have an ATI Radeon HD 3650 PCle x16 video card in an HP desktop. The
back
of the video card has 3 ports: 1 DVI and 2 DisplayPort.

We would like to have 3 monitors hooked up to this desktop. When we
contacted HP support about this desire, we were assured that 3 monitors
could
be connected directly to the video card WITHOUT the need to split to
connection with a special adapter.

However, when we connect 3 flat-panel monitors to this video card-directly
to the 3 ports-only 2 monitors function at any given time.

This is also true when we try other hookup scenarios, like using the 2
DisplayPort ports and splitting one of the connections to 2 monitors.

We are assuming therefore that the general rule with any video card is
that
is can only be used to 2 monitors at any given time?
Click to expand...

As a general rule, while you can connect 3 monitors to your graphic card,
only 2 can be active at any time. Although cards can vary in this, the ATI
card you have indeed can only have 2 active displays.
 
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