I currently have an nVidia GTX 480, with two DVI ports and one HDMI. I have the two DVIs plugged into 1680x1050 resolution monitors and the HDMI into a 1080p HD TV.
Currently Windows7's screen resolution tool will only let me have one monitor + TV or 2 monitors and no TV showing extended desktops at a time. Is this a software or hardware limitation?
If I get better multi-monitor software will I be able to extend my desktop across all three screens?
You can connect 3 monitors, but one will be disabled. The point of having the 3 ports is to give you options, so you can choose between using DVI or HDMI. Here's a quote from a thread on the NVIDIA forums when someone asked about multiple monitors on the GTX 480
For graphics cards which have a single GPU onboard like the Geforce GTX 480 or 470, only two displays can be active at the same time even if the card has three physical monitor connectors. Some cards like the older version of the Geforce GTX 295 have two GPUs onboard and three display connections, two DVI and one HDMI. The first two ports, the two DVI ports are connected to the first GPU and the HDMI port is connected to the 2nd GPU. So in this case, three monitors could be supported as long as the card wasn't set to "multi-GPU" mode. But for pretty much every NVIDIA graphics card, you will only be able to activate two monitors at the same time.
This is a hardware limitation. I suggest purchasing a cheaper card like a GT 220 and putting that in to add more monitors.
