# Building new system, need advice. (three screens)

## usui

Hello everyone.

I've decided to build a new computer to which I want to connect three screens. I have already bought 

a few pieces but I have not yet bought the monitors nor the graphics card. The relevant pieces I already

have are:

2 x Xeon x5675

Intel S5520SC Workstation Server Board

Just so you guys know without having to google anything this motherboard has 2 PCIe 16x lanes and crossfire support 

BUT NO SLI!

Now I'm using 1 screen with 6 virtual desktops (standard xfce4). On the new system I would basically want the same thing 

except that I should be able to see three of the displays simultaneously. 

The monitors will be running at 1920x1080.

The current graphics cards have three outs so I was thinking that this should be possible with one high end card but I would like

someone to verify this. I would be buying a high end card preferably nvidia because I have been using nvidia cards on my linux

boxes for a long time without serious issues. However if you guys think that this setup is not possible with one graphics card I 

might buy two ATI cards (because I have crossfire support but no SLI). Or do you guys think I would still be better off with two 

nvidia's? I'm not a gamer and if I'm not mistaking SLI is mostly interesting if you are using a lot of graphics bandwidth to give your motherboard

a bit of a brake because with SLI the cards can also communicate directly (without using the PCIe lanes, the lanes are offcourse 

also being used next to the direct connection). 

If I have to buy 2 graphics cards I would also opt for two high end cards however I would prefer to just buy one.

It seems logic that the performance will be better with two but seeing I'm not a gamer and not someone who likes paying more

to get the same result please don't advice this if I wont notice the difference. Also I'm not using any special heavy graphical rendering software

or anything like that but I would expect the three screens on full hd to be able to show hd movies on each screen without flaw obviously.

I'd also like to be to use a little eye candy (like compiz-fusion).

If you need anymore info on what I'll be doing or other hardware pieces that may be important for this "problem" feel free to ask offcourse!

THX FOR READING THIS POST even if you can't advice me  :Wink: .

Regards,

Usui

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## chithanh

Avoid multi-GPU configurations, they don't really work well in Linux. There are a few Nvidia cards that support 3 Monitors, for example the EVGA GTX 460 2Win, but they normally use two GPUs.

If you run nothing more demanding than Compiz, then a 5450 or better AMD card with DisplayPort will be ok. If none of your monitors has a DisplayPort connector, then you need an active DP->DVI adapter too (cost: $20).

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## BitJam

I concur. I've used nothing but Nvidia but I too would suggest using an ATI/AMD card with displayport for your three monitors.  If you use more than one GPU and you want to be able to drag windows from one monitor to the other then you will be forced to use Xinerama built into the X-Server which sucks.  If you don't want to drag windows between monitors then multiple GPUs should not be a problem.

Also, you should be aware that the system will see one large x-screen stretched across your three monitors.  It's not quite the same thing as a separate desktop on each monitor.  You will probably need to knit together background images manually.  I use the Imagemagick convert command for this.  I can post a Bash script I use for doing this with two monitors. 

Your Xeons should be able to deal with HD decoding no problem. I've got a dual-core 2.7 gig processor and I needed to use Nvidia's VDPAU (which moves HD decoding onto the GPU) in order to get seamless performance.  I don't know where ATI/AMD is at in this regard.  Also, the last time I checked, enabling composite conflicted with vsync on video playback which means you might have to choose between Compiz-Fusion and tear-free video playback.  This is with an Nvidia GPU.  I don't know if there is a similar problem with ATI/AMD.

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## s_bernstein

Maybe you should look for a nvidia quattro. There are some, which supports up to 4 monitors, but I must admit, I don't know if they are using more than one GPU.

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## usui

Hi guys,

Thanks for all your responses. I have however another idea. I would buy a high end nvidia graphics card (like gtx 480), not the absolute 

latest because the price premium is a rip off (considering what I'll need it for it wont make a difference anyway). 

Then I would connect this card with the matrox triplehead2go (http://www.matrox.com/graphics/en/products/gxm/th2go/).

That way my linux wont give me that much of a hard time (hopefully). This would also stretch the image over the three monitors. I would have

preferred to have three separate desktops but as long as the programs maximize on one monitor it is acceptable. 

I found a guy who got this working rather easily under linux (I did get some errors about certificates with his site, I'm just saying so you're warned):

https://blog.venefyxatu.be/blog/archive/2009/02/18/matrox-triplehead2go-and-linux.html.

I have contacted Matrox asking if there are any known issues with Gentoo and I'm still waiting for a response, I'll let you guys know.

Also by using one rather high end card I would be able to game if I wanted (I probably never will since I don't have the time but you never know,

I believe it's better to have the possibility to do it but not the time than the inverse  :Wink: ).

chithanh --> I have been looking for several solutions for my problem and had NOT come across this card, I understand that it is not that interesting considering

the dual GPU but I'm glad I know of its existence now  :Wink: .

BitJam --> I would definitly appreciate to see that Bash script of yours  :Smile: . I can then take a look to see if I can change it to "support" three screens. If I will have

to choose between tear-free video and compiz I will definitely go with the tear-free video  :Wink: .

I am surprised though that you're both advising me to get ATI cards. Has the linux support improved so much over the last years in comparison to nvidia?

s_bernstein --> I have looked into this. The number of cards that support 4 displays (the alternative is 2, not three) is limited. These cards belong to the NVS family

http://www.nvidia.com/object/quadro_fx_product_literature.html and if you look at the performance tab on this sheet http://www.nvidia.com/docs/IO/40049/LC_QUADRO_4000_forMac_US_Mar11_LR.pdf

then you will see that the performance of these cards is rather limited. Also if you compare it to the non-professional cards http://www.nvidia.com/object/graphics_cards_buy_now.html it

is apparent that these cards are rather weak. 

I would like to here your ideas to the triplehead2go - high end nvidia card idea. Do you guys foresee any problems or disadvantages compared to your solutions?

Thx for your input.

Regards,

Usui

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## chithanh

AFAIK the TripleHead2Go needs to be configured in Windows once, but then works under Linux too. However the TripleHead2Go has limitations regarding the maximum resolution. And it is very expensive, around the price of a high-end graphics card.

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## usui

 *Quote:*   

> AFAIK the TripleHead2Go needs to be configured in Windows once, but then works under Linux too. However the TripleHead2Go has limitations regarding the maximum resolution. And it is very expensive, around the price of a high-end graphics card.

 

Thx for your input. The windows thing is not a problem because I always dual-boot on my systems (just for the times that I am forced to use software which only works on windows) with windows 7. The limitation of the resolution is not something I"ll notice. I'll be running 3 24" screens each running on 1920x1080 --> times three this gives me 5760x1080 and this is the max 

resolution supported (http://www.matrox.com/graphics/en/products/gxm/th2go/).

The price is acceptable as well: http://www.flevowebwinkel.nl/product/954717/matrox-triplehead2go-dp-edition-digitaal-t2g-dp-mif.html?ref=2#description

On this site (and this is the cheapest I found) the price is 260 euro which is about 370$.

So I think I'll leave this post open for a couple of more days and then I'll procede to buying the items if no one has anymore objections or ideas.

Regards,

Usui

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## BitJam

 *usui wrote:*   

> I am surprised though that you're both advising me to get ATI cards. Has the linux support improved so much over the last years in comparison to nvidia?

 

IMO it has.  My uncle recently got a computer with an ATI graphics card.  I helped him get Linux running on it over the phone and he was able to use a simple GUI program to get it to do the equivalent of TwinView.  I was very impressed.    In addition, IIRC, ATI is making (or has already made) their drivers open source.

Ever since an Nvidia guy emailed me a patch for the Andrew Morton kernel around 2 am on a Saturday night, I've been a die hard Nvidia fan.  The patch was to fix a bug in the kernel that was triggered by the Nvidia driver.  OTOH, their closed source drivers continue to be a pain.  Even with composite disabled there have been ongoing problems getting vsync to work properly.   

Here is the script I used to put the same background on both screens in TwinView:

```
#!/bin/bash

size1=1600x1200!

size2=1920x1200!

name=${1%.*}

ext=${1##*.}

echo "size1 = $size1"

echo "size2 = $size2"

#echo "name = $name"

#echo "ext  = $ext"

tmp1=$name-1-tmp.$ext

tmp2=$name-2-tmp.$ext

echo

echo "tmp1 = $tmp1"

echo "tmp2 = $tmp2"

convert $1 -resize "$size1" $tmp1

convert $1 -resize "$size2" $tmp2

convert $tmp2 $tmp1 +append $name-full.$ext
```

It should be easy to generalize to 3 screens.  The exclamation points after the sizes are significant.  I don't remember what they do but I do remember they were required to make it work correctly.

The TripleHead2Go is a good solution but I would still suggest you consider getting an ATI card, especially if you might ever want to go to four screens.  I've also seen hacked versions of libXinerama that allow you to manually specify the xinerama layout.  I don't remember the context that made this useful/needed.

Also, I'm sure you know that you also need to emerge programs with the xinerama USE flag in order to take advantage of xinerama.

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## chithanh

Be sure to read the fine print at the bottom of the TripleHead2Go page and buy in a shop where you can return the hardware when it does not meet your expectations.

btw. the cheapest AMD card that supports 3 monitors and Compiz costs less than 50 EUR. http://www.perfect-systems.nl/info.asp?info=164090

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## usui

Hi guys,

Thx for your posts ones again  :Wink: .

BitJam --> Thx for the script and I guess I'll buy an ATI card then. I was thinking of going for the RADEON HD6950. Chithanh I looked at the card that you posted and I don't doubt that this 

would be sufficient for running compiz TODAY. However building a computer like this takes a lot of time and this one, IMO, will cost a pretty penny. I mean that this computer should be 

a bit future proof. I think you'll agree that chances are rather slim that your card will run compiz perfectly in 5 years or so. However if I use the HD6950 (true it will cost a bit more) I probably 

wont have any trouble with this.

Bitjam I indeed know that I will have to adapt the USE flags to my new setup, I hadn't specifically thought about which flags I would have to use but the xinerama flag makes sense  :Wink: .

Chithanh, good thing you pointed out the fine prints (I had looked at them briefly (which is why I knew that I had to mail about the matrox gentoo support)) but apparently the resolution I 

want is only available using 50hz and the monitors I was going to use (samsung 2450H) works on 60hz when it uses 1920x1080). Looks like my quest for all the right parts isn't over yet.

Anyway thx again for everyone's ideas  :Wink: .

Regards,

Usui

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## usui

Hi all,

The matrox is no longer an option. I just got an email from an employee of Matrox:

Hello Usui

The 5760x1080 resolution is only supported under Windows.  It is not supported under Mac or Linux OSes.

I have checked with the product manager regarding Gentoo Linux and I have been informed that this should not be a problem.  However, the maximum TripleHead resolution is 3* 1280x1024.  If you want higher resolutions, then you can use the DualHead2Go, which will run two displays at 1920x1200.

Please be aware that you need to have DP out of your graphics card for the TH2Go DP or DH2Go DP to run properly.

Regards

Andrea

--> So I guess I'll look for one high end graphics card with one GPU and two DVI's and a display port. Can it be a simple HDMI connection instead of a display port?

Thx.

Regards,

Usui

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## chithanh

If you buy the Sapphire 5670/5770/6850/6950 Flex, then you can connect 3 DVI/HDMI monitors to one graphics card. For all other cards you need one DisplayPort monitor or an active DP->DVI adapter (cost: around 20 EUR).

 *usui wrote:*   

> I think you'll agree that chances are rather slim that your card will run compiz perfectly in 5 years or so. 

 A 5 year old low-end Radeon X1300 will run Compiz just fine.

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## usui

I just bought the SAPPHIRE Radeon HD6950 2GB GDDR5 (new) for 190 euro (270$) which has DVI and mini DP.

The monitors I'll be using have DVI and DP so it should work. I'll post the things I have to do in order to get it to 

work properly (If I don't forget and I'll try not to).

Chithanh with this card I'll be able to game as well (if I find the time), If I were a 100% certain I would only use 

this computer for compiz then you are probably right about buying the Radeon X1300. However I am quite certain 

that it is a fact that I'll go further with this card then with the Radeon X1300 (I won't be obliged to buy a new card soon

because of lack of performance or something similar). And like I said I want this computer to be a bit

future proof.

Anyway thank you for your help as well as everyone else who gave me their point of view.

regards,

Usui

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## usui

Hello everyone,

Because I said I would post the things I needed to do to get my setup working I thought this was as good a time as any.

First of all getting the three screens to work was truly a breeze! I didn't change my Xorg.conf or anything and just used 

the ATI control center app (which you should obviously emerge). I have the option to enable xinerama but this does not seem 

to be necessary and I would advise not to do it. I can transfer windows across all of my monitors without issues. Before I had 

my displayport cable I was only able to connect two screens at once. When I did this I had immediately enabled xinerama. After

enabling it I saw that whenever I moved my mouse cursor to screen 2 my cursor became corrupt (it turned into some kind of weird square).

This did not change after rebooting. It was a constant flaw. 

Sometimes I have the same problem with the current non-xinerama settings but it dissapears quickly after moving the cursor to another 

screen and back.

I do not know why the xinerama option is still available in the ati configuration screen but I have just started multiple screens so maybe 

I'll find some issues in the future that do require xinerama (which would be weird since the project is no longer maintained since 2007 or something like that.)

Anyway Cheers,

Usui

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