Matrox G450 Dual Head

A product review of Matrox's dual-head video card.

Once upon a time Matrox graphics cards were marketed to people building everything from value consumer desktops to gaming rigs to high-end, PC-compatible workstations. Though even Matrox's fastest G-series has fallen far behind the competition in terms of raw 3-D performance, thus losing the gaming and consumer markets, they remain popular in the workstation market due to their reputation for stability, high-quality visual output and excellent Linux driver support. I will examine the Matrox G450 dual-head video card, with regard to both the usefulness of dual monitors and how well the G450 handles running two monitors. My test system is a 560MHz Pentium III supported by a 440BX chipset and 384MB of RAM running Linux Mandrake 8.0 (kernel 2.4.4 and XFree86 4.0.3). My video card is, of course, a Matrox G450 with one 360MHz RAMDAC, one 230MHz RAMDAC and 32MB of DDR RAM on board to drive two VGA outputs.

Setup and First Impressions

Having found X to be a common source of issues in the past, I wasn't looking forward to configuring this setup. Much to my surprise it was quite easy, with just one stumbling block--upon installing the card, Mandrake incorrectly recognizes the G450 as a G400. This isn't a big deal as they are very similar cards. After I had the card physically installed in the computer I went to Matrox's web site to download the latest drivers, choosing the Matrox-authored but closed-source binary version. The binary drivers are installed by simply dropping the two binaries into your /usr/X11/lib/modules/drivers directory. Updating your X configuration to reflect the new setup is similarly easy.

First, add one or two monitor entries (depending on whether your two displays are of different capabilities):

    Section "Monitor"
    Identifier "monitor"
    VendorName "Unknown"
    ModelName  "Unknown"
    HorizSync   31.5-57.0
    VertRefresh 50-90

Add two device entries for the G450, one for each port (see Listing 1). Then add two screen entries, again one for each port (see Listing 2).

Listing 1. Adding Two G450 Device Entries

Listing 2. Adding Two Screen Entries

Tell X how you want the displays to be logically oriented with respect to each other. Most people will probably want a horizontal layout. Also tell X that you want it to join the two displays together into one virtual display--I opted for two XGA screens so the resulting desktop will be 2048 x 768 pixels (see Listing 3).

Listing 3. Server Layout Subsection

Write the config to disk, restart X and you're done. Listing 4 is a complete copy of my X config, and Matrox's own documentation ( explaining how to set this up is actually quite useful.

Listing 4. Full Copy of X Config

How It Stacks up

With Xinerama enabled the G450 handles the dual outputs quite well despite Xinerama's disabling DRI. The first visual artifact I noticed was a slow update if solid window dragging is enabled (via KDE in this instance) and a large window is dragged from one screen to the other. This really didn't bother me too much, but it has the potential to turn into more of an issue if one has a large window spanning both screens displaying animation of some sort. The other visual artifact stems not from the video card itself but from the monitors: because I used two similar 17" monitors and had them both running at the same resolution and refresh rate, there was a small amount of crosstalk resulting in a subtle grey band that slowly (approximately once per two seconds) but repeatedly progressed over each screen vertically (going up on one, down on the other). I found it to be vaguely annoying but really not much compared to the benefits of having two monitors (see next section).

I did try running dual displays without Xinerama, and this resulted in two separate desktops that shared little other than the mouse pointer. Logging into KDE resulted in two separate desktops; one came up with the usual compliment of toolbars and icons and the other with the toolbar but no icons other than the trash can. Windows could not be dragged from one screen to the other and due to this I found the configuration substantially less flexible and useful than Xinerama mode. Overall the G450 handled dual outputs just fine.

But is it really useful? In a word, yes. Being able to have not only two monitors going but to have them running off of the same login on the same machine is amazingly helpful. I found that I ended up switching between just three modes of use most of the time: lots of shell windows (six or eight) covering both screens, shell windows on one screen with web browser windows on the other and web browsers covering both screens.

The second configuration is how I use the machine most of the time, as it allows me to read documentation, etc., from the Web while I work at the command line or write. The first configuration came in a close second as it allows me to watch logs, IRC (I follow several channels on from time to time) and read man pages, all while I work at a command line. The third I use mostly when I catch up on the news or when I'm researching a topic covered on many different web sites (comparison-reading). Other cool or useful suggestions I've heard of include: 3-D modeling, with blueprint view and toolbars on one screen and perspective/preview on the other; programming, with editors on one screen and debuggers on the other; running emulators, with the native environment on one screen and the emulated operating system on the other; network debugging, with command lines on one screen and tailed logs on the other; and watching a DVD on one screen while in IRC on the other (okay, so this is cool but really not useful).

There are truly a lot of things a dual monitor configuration is good for. There is only one major downside to any dual-monitor configuration; however, having two monitors on your desk consumes a lot of real estate. Unfortunately, there are really only two ways to work around this issue: get a bigger desk or get smaller displays (e.g., flat panels). Another (albeit minor) issue is that in a dual-monitor configuration certain default GUI behavior that makes a lot of sense on a single display doesn't make any sense at all. The most significant of these is that the once-convenient default placement of many dialog boxes and prompts in the center of the screen suddenly becomes very irritating due to the message being split between two displays. Despite these disadvantages, however, a dual-monitor configuration will undoubtedly be useful to many readers.



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Re: Matrox G450 Dual Head

Anonymous's picture

I had similar results to ChoongNg's when testing the G450 DH. I greatly enjoy the Non-Merged MultiHead mode. Merged mode is nice too and I have found myself using it on several occasions.

3D acceleration seemed to work just fine in Merged mode, though as the docs say, this is the only MultiHead mode that supports it. Not a big deal for me since I don't use anything that would need it. There are no screen refresh issues for me using KDE at all anyway since I run a SMP PIII 1ghz machine and have ram to spare for eons. Lucky me. If you aren't lucky enough to have someone else paying for your toys, then you may see some issues with screen redraw slowness. I HIGHLY suggest the 32mb cards over the 16 as otherwise you will not be able to run both heads at a high resolution (I like 1600x1200 on both but 4.1 has a bug that somehow makes it 1280x1024/1600x1200 at the highest unless you are in merged mode which you can run at 1600x1200, and I hear this is fixed in 4.2 so that you can do 1600x1200/1600x1200 in non merged mode). I however only have PCI in the machines I have these cards in and so I have no idea how well the 16mb AGP cards do.

My largest issue with the mga drivers is that when switching to a virtual console, very strange things happen. This may not be the case under every setup however for me I have found no way to get the virtual console to work right. I am able to type things into the console and have them run, but seeing them is another issue. None of the fixes for that problem I have found seemed to work for me including running fbset a couple of times to clear things up. As I understand it this problem is comprised by a few different bug_features in matroxfb and XFree86 mga drivers.

IMHO some wonderful angel needs to work with the matroxfb folks and those that write the non-matrox mga driver to get things straightened out. Of course, fixing these issues may be larger than that. If there is a wonderful angel who can do it, my thoughts are with you Jedi and I wish you light speed. I also wish I was you cause I'd be making more money somehow.

My BIG Wishlist item: Multihead X with the virtual consoles assigned to the frame buffers evenly (or however you like), and the ability to hit ctl-alt-f(x) and have only the screen attached to the frame buffer I am requesting to display the virtual console switch out to do so. In other words, the screen that isn't going to display the requested console should continue to display X and be useable. Who cares if the mouse still seems to let you run entirely off the screen. In this way one could run X-Con or X-X or Con-Con as they need to.

Of course, I'll be more than happy just to have matroxfb and the X mga driver work together.

(Some of the issues with these things *might* be better fixed in 2.4.19 [not out yet at time of writing] and XFree86 4.2. I myself won't be running 4.2 until Branden of Debian fame gets to huck off 4.1 as a stable package for Woody and gets to do some work on 4.2. Go Branden! It's almost time! Kinda! :)

To summarize my feeling about the G450 DH, I love it and I've got 4 of them. 2 of them even live in a single machine doing remote X displays. I look forward to better support as time moves forward, and for Matrox to release the HAL source code and many other things to happen, that will make these cards really rock and roll.

Does anyone have any tips/tricks to getting these cards working really well? Please! Post them! I'll try to do the same as my testing continues.


Re: Matrox G450 Dual Head

Anonymous's picture

Just wanted to say that Matrox REALLY impressed me with their PowerDesk app. Good to know that some companies truly are Linux friendly. If they only could get some decent 3D acceleration I'd buy a lot more from them! :-)

Re: Matrox G450 Dual Head

Anonymous's picture

Hey Guys,

This is the second article with a sub-file that blows up. "Listing 3. . ." once again takes me to the search window with a no resukts message. Tighten up your links!

Re: Matrox G450 Dual Head

scott's picture


I'm not going to have time to track down every comment, so if you find something that's not working, send me an email.



Re: Matrox G450 Dual Head

Anonymous's picture

The window popping up in the middle of your screen is because your windowmanager is not Xinerama aware.

Enlightenment was one of the first windowmanagers to address this issue. Give it a try.