Three monitor setup for Mac Pro 2008?

I'd like to connect three monitors (for example 3 x Asus VN247h + 1 x Ax Triple Monitor Stand AXM4200) to my aging but still perfectly serviceable Mac Pro 2008 (MacPro 3,1 - A1186), so I need to find out what model of graphics card I can use.

I currently have a Nvidia GeForce GTX 285, but it only has two DVI ports, so I'm missing a port for a three monitor configuration.

Is there any graphics card compatible with that ancient Mac Pro model that can drive three monitors?

Can I install two graphics cards (two ports each)? What model would be compatible (hopefully more powerful than the GTX 285)?

It's hard to find information about older Macs and compatible upgrades online, so I really hope that iFixit's great community will be able to help me out with some advice! Thanks!!