Would like to run 3 monitors. Any suggestions on a graphics card?

If you have a 450 watt or greater power supply, I can recommend what I use -- Radeon HD 6770.  It has three outs (HDMI, DVI and displayport) and can drive three monitors.  Max resolution is 2560x1600 for DVI and displayport outs, 1920 x 1200 for HDMI out.  It features smart power management and can use the AMD EyeFinity feature to create one giant display from multiple monitors (best with identical monitors <=1920 x 1200 resolution). 
Cost is around $75 - $100 since it's years from being state-of-the-art.
I use it with SONAR X2a with no problems on dual monitors.

Have a look at the Matrox 9140.
 http://www.matrox.com/graphics/en/products/graphics_cards/m_series/m9140lppciex16/
 
It is PCIe, supports up to 4 monitors via a breakout cable dvi or analog and is fan less and somewhat pedestrian which is good for a DAW. Make sure you can get the drivers for it for your OS.
 
We use one at our church to drive our presentation displays.
We got ours on eBay for a song.
 

am currently running 4 monitors on Asus DCUII HD 6970. 
http://www.asus.com/Graphics_Cards/EAH6970_DCII2DI4S2GD5/
 
its an older card however, according to specs it is capable of running up to 6 monitors. 
 
the Asus DCUII series has almost the same output connectors (2 DVis + 4DPs). The DPs will make way for flexible connectors via adapters. (there are several types avail)
http://www.techpowerup.com/img/10-08-31/189a.jpg
 
hope this helps... cheers!!!

you could use a dual one + the onboard mobo if you wanted / have one ? just a thought. or the quad sort, or 2 SLI's  ? 
 
 
 

Thanks for the replies! I was just wanting to be able to avoid getting one that may be known to cause issues with X2a.

rodreb
Thanks for the replies! I was just wanting to be able to avoid getting one that may be known to cause issues with X2a.

As a rule of thumb the more "game oriented" a display adapter is, the more it hogs the bus it is connected to. Matrox adapters are generally for business, and give way to the daw audio stream by default.
 
 

I've had several Matrox graphic cards (they had only 2 outputs though) and they have been very well known for being working nicely with DAW's. 
 
Now I have a NVIDIA NVS450 which is quad output. Fanless. Working very nicely, but I don't have X2a though. Or X1 for that matter. :)

I've used a pair of PNY nVidia GS8400 cards for years. Both are single slot PCIe, fanless, and have two HDMI outputs each. They've driven three monitors like a charm.
 
Recently I upgraded to an HIS AMD HD7850 to add more GPU acceleration to the system for video editing. However, the catch with using three monitors off of a single AMD GPU is that one of the monitors must be connected to one of the DisplayPort outputs. Furthermore, the connected monitor has to have a display port input or an active Display port to DVI adapter must be used to connect to a monitor with a DVI input. Passive adapters will not work when connecting a third or more monitor.
 
What complicates things further is that not all monitors, at least in my experience, work with active DisplayPort adapters. I've got a pair of LGs and a single Acer monitor and none of them work with the active adapter (they work with passive DisplayPort adapters and all other sources). However, I have an old junker monitor with no stand that I keep around for testing and it works with the active DisplayPort adapter. Go figure.
 
I'm not saying AMD cards can't work with three monitors. Clearly they can. There's just some caveats in my experience. From what I have read, however, the latest nVidia cards with 3+ outputs do not require active DisplayPort adapters to work with three monitors. I haven't tried any out but will soon ...

I'm using a Radeon 6950, 2dvi outputs plus display port...under windows 8 monitor management runs perfect!