How much video card memory for a quad monitor setup

[koshcu]

I am about to get a 6000 series ATI card so I can run 4 monitors off one card more cleanly. I am going to be using this for work and it will not be used for games at all. However I do need enough memory on the card for things like compositing to work right.

How well does the catalyst drivers work for just 2D desktop work with eyefinity right now? Right now I have dual nvidia 8800GTS cards and I have to run them as two seperate x screens since xinerama stopped working a while ago. This is a major pain in the neck.

I will just be running kde 4.x with it and 4 24inch monitors with browsers, code editors etc and play some videos. I don't really know how much memory on the card composite needs to work efficiently.

Do I need a card with 2GB of ram or is 1GB okay?

[bridgman]

Just to give you some rough numbers, if your 24" displays are running at 1920x1200 that's about 2.3M pixels. Assume triple buffering plus Z buffer plus another buffer for the compositor at 4 bytes/pixel each, so 5 x 4 x 2.3M bytes per screen. With 4 displays you should be consuming a bit under 200MB (vs say 50MB for a single display), so a 1G card will still have a lot more free memory with quad displays than a 512M card would have with a single display.

The big question IMO is whether you will be using the extra screen space to run multiple video-memory-intensive apps at the same time. If you are, that's where the 2GB cards come in. If you are typically going to be running only one memory-hungry app plus a bunch of smaller apps then 1GB should be OK. If your memory-hungry app runs well on a 512M card or you don't have any seriously memory hungry apps then you should definitely be fine.

Based on the application mix you listed above 1GB seems like it should be all you need.

[koshcu]

What would qualify as a video memory hungry app? I know games would along with things like blender probably but I don't use those. I doubt playing videos is video memory hungry.

It is just that I am building a new machine and I would like to make sure I do a fairly good job.

Going to get a 990FX motherboard with a Phenom 1100T processor and 16G of ram and a Seasonic 460FL power supply. That should make it easily fast enough for all the tasks I need to do with it I would just like to be able to put a lower power video card in it then the 6950 I was looking at which has 2GB so if 1GB will work I can drop WAY down in power usage and make the system much quieter.

I pretty much do DB development and testing so mostly I needed cores and RAM and right now the AMD systems seem to be much better priced for that and lower power usage when considering the entire system.

I also want to stay away from Nvidia video cards for now since I run 4 monitors and xinerama is no longer a working option so that leaves eyefinity from AMD cards.

[chithanh]

If you don't plan to do any gaming or GPU compute, then the 6950 is serious overkill. The extra video memory is used for textures mostly.

Besides, running a 200W graphics card, a 125W CPU + mobo + RAM + drives off a 460W PSU is already at the edge of the comfort zone.

Possibly the Sapphire 5670 Flex or a 6870 would fit that setup best.

[energyman]

well, back with my old 3870 I ran:
770 based board
Phenom II 955BE
8gb ram
couple of disks

of a 450W BeQuiet PSU and had plenty of room. We are talking about 100W idle/normal desktop usage, 160W typical high load and 270-290 artificial high load.

Even with todays setup, 6hdd, one SDD, 955BE, 5770, 880G chipset,4x14cm, 2x12cm system fans the PSU is bored and not seriously taxed most of the time

So as long as OP does not start using a 200-300W card he should be fine.

[koshcu]

Hmm I think I am going to need to go with a 6950 1GB card for practical reasons.

Very few of the 6000 series cards will actually run more then 3 monitors even though the chips inside are capable of supporting it. I have 4 monitors that can use HDMI or a DSUB connector and the DSUB connector actually works better for some reason. With the HDMI connector they won't go to sleep. I have tested with HDMI vs DSUB at 1920x1200 and can see no difference of any kind between them.

Converting displayport to DSUB is very easy and cheap. Converting the other stuff to DSUB or HDMI is over pretty expensive. I was originally looking for a eyefinity 6 card but they are also a lot louder and same power usage as the 6950 that I found.

http://usa.asus.com/Graphics_Cards/AMD_Series/EAH6950_DCII2DI4S1GD5/#specifications

That card has 4 displayport that I can convert to DSUB for far less then the other cards I have been looking at. The card requires more power then the lower end 6000 series cards or 5000 series cards but the reviews also say it is very quiet and runs cool. Also from what I found on forum searches the 460-FL should power it just fine but I may go to the 560 model.

However knowing I only need 1GB makes it much simpler since the 2GB models are HUGE and heavy and chew up more power.

[curaga]

How about the Flex models? Three non-displayport displays without convertors.

[koshcu]

I have 4 displays and I could not tell for certain if that flex card would work with 4 displays. Also most of those interfaces are DVI-D which I can convert to HDMI I think however I can't convert them to DSUB I don't think. I would prefer to use DSUB so that my monitors will go to standbye correctly. For some reason with HDMI connectors my monitors go to full power and a blue screen when the computer tries to put them to sleep but with DSUB it works fine.

Things just end up so dang complex. If HDMI would allow my monitors to power down correctly I would probably use HDMI. Other then that one issue I love my monitors. Nice S-PVA panels 24inch 1920x1200.

[energyman]

wut? dsub? That crap is horrible!

Why do you care about sleep anyway? If you go away for a while:

xset dpms standby/off

done

[koshcu]

That won't turn my monitors off if an HDMI connector is used. Actually I found a bunch of monitors that do the same thing. I have also done testing with swapping HDMI to DSUB back and forth on these monitors and done it with various testing images and I and others I have had look can see no differences of any kind between DSUB and HDMI at 1920x1200 which is native resolution.

It is true that some monitors do have a bad DSUB connector but mine work very nicely.

Most professional review sites can't find any difference between DSUB vs a digital connector so it seems like a silly thing to say is bad. Almost like people wanting to get a $200 HDMI cable vs $10 one when reviews say they are 100% identical.