Dual/Quad head frame buffer questions.

[BatmanNate]

My boss is looking to order video cards for our new computers that support between 2-4 monitors, both CRT and LCD. The multi monitor functions must be done in hardware, I'm not sure if this means independant frame buffers or what (I don't know much about the intricacies of graphics cards) but it must not lag windows at all. The machines will be running XP and have AGP slots. Any information that you guys have to point me in the right direction would be greatly appreciated. 🙂

EDIT: Update below.

 

[JustAnAverageGuy]

Matrox parahelia.

What exactly do you do with these computers?

You may end up having to get a combination of both AGP AND PCI cards.

 

[BG4533]

To get 4 heads you are going to have to use the PCI bus.

You can get a Matrox Parahelia that will support either dual DVI or Single DVI and 2 VGA. Then you will also have to throw in a PCI card.

If you are going to be doing any rendering or very resource consuming things you may want to look into PCI-X.

You really need to let people know what you plan on doing so we can give you an idea on more specific cards and other stuff.

 

[BatmanNate]

Found this one and it looks like it fits the bill:

G450 Multi-Monitor
G45X4QUAD-B

Quad Analog or Quad Digital DVI support, Four G450 graphics chips, PCI Bus , 128 MB of DDR memory (32 MB independent frame buffer per chip), 360Mhz RAMDAC per chip, supports multiple cards in one system
Maximum analog resolution : 2048x1536 32bpp @ 85Mhz per display
Maximum digital resolution : 1280x1024 32bpp @ 60Mhz per display (1600x1200 with DVI panels that support reduced blankings)
Measurement : Height 3.8" / Length 6.5"
Two LFH-60 connectors, Two one foot LFH-60 to 2xDVI-I cables
(DL-CAB-DVI) and four analog adapters included


It actually maintains 4 independant frame buffers, and has 4 cpus an 32mb memory per CPU. Lowest price I've found however is a hair under $700.

 

[BatmanNate]

So I guess this pretty much establishes the high end ideal, my next question would be about the mid range cards. Do they all split the frame buffer in hardware or does the system CPU make the secondary/tertiary/etc buffer calculations and just bus it over the AGP/PCI bus to the card's buffer memory for output to the GPU? (ie software) Is it necessary to have independant frame buffers with dedicated GPU's on the card to achieve this?

Also, the multi card suggestions are not much of an option as that tends to flood the PCI bus.

 

[Cerb]

Well, what will your people be doing? If there's no need for any 3d use, then get several PCI and AGP cards, and see how well they mix and match (particularly multiple Matrox, multiple NVidia, and multiple ATi).
In theory you can mix and matxh any cards and be fine, but that's not reality.
For LCDs, DVI to DVI is the way to go. Even if you don't notice crawlies with the HD15, there's a good difference, and you won't strain your eyes as much.

The PCI bus won't be flooded if things are done right (unless you've got some high-quality video being done in software, but even then maybe), but unless you mention what is being done that will use the rest of the PCI bus, we can't give you much more in the way of suggestions.

Based on gut feeling, I'd say try two similar cards, like an AGP Radeon 9000 Pro, and a PCI Radeon 9000, and see how they work together, using four monitors, each at a nice resolution and framerate. If it isn't being done as much in hardware as if there were only one video card and one display, you'll be able to feel the difference right off.

 

[BatmanNate]

Originally posted by: Cerb
Well, what will your people be doing? If there's no need for any 3d use, then get several PCI and AGP cards, and see how well they mix and match (particularly multiple Matrox, multiple NVidia, and multiple ATi).
In theory you can mix and matxh any cards and be fine, but that's not reality.
For LCDs, DVI to DVI is the way to go. Even if you don't notice crawlies with the HD15, there's a good difference, and you won't strain your eyes as much.

The PCI bus won't be flooded if things are done right (unless you've got some high-quality video being done in software, but even then maybe), but unless you mention what is being done that will use the rest of the PCI bus, we can't give you much more in the way of suggestions.

Based on gut feeling, I'd say try two similar cards, like an AGP Radeon 9000 Pro, and a PCI Radeon 9000, and see how they work together, using four monitors, each at a nice resolution and framerate. If it isn't being done as much in hardware as if there were only one video card and one display, you'll be able to feel the difference right off.

We will have some high speed SCSI drives on this bus as well as some intensive network activity. (We have data processors and programmers that are going to use these) The boss is set on using single cards that are hardware based.

I myself have run triple head with a GF3 and two Matrox PCI cards, as well as dual head with a 9700 pro and felt no discernable lag due to the video under XP (and this is including games) however he wants to be certain that we're not going to have to deal with drawing one frame buffer in software, we need both in hardware.

On a somewhat related note, I have suspicions that the card that will span a video across both monitors supports drawing both buffers in hardware as it would probably be impossible to split the overlay otherwise, correct me if I'm wrong. We have no need for 3d so if anyone has suggestions on strong multihead cards that don't need strong 3 (no parhelia either) I'll have them.