cub_fanatic :
I'd keep the motherboard and buy a new single good GPU and you'll probably need a new power supply as well. The main question is what is your budget? You can replace the 720 with just about any GPU out right now. Unless you really want SLI, Crossfire or CPU overclocking, there is no need to replace the motherboard.
I need to run three 21.5" monitors now and i want the chance to upgrade the configuration to 6 monitors in few months for a trading-online PC. My configuration will be the following
CPU Intel Core i5-4590 3.3GHz Quad-Core Processor
Motherboard Gigabyte GA-B85M-D3H Micro ATX LGA1150 Motherboard
Memory Crucial Ballistix Sport 16GB (2 x 8GB) DDR3-1600 Memory
Storage Crucial BX100 250GB 2.5" Solid State Drive
Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive
Video Card EVGA GeForce GT 720 1GB Video Card
Case Fractal Design Core 1500 MicroATX Mini Tower Case
Power Supply XFX ProSeries 450W 80+ Bronze Certified ATX Power Supply
Optical Drive LG GH24NSC0 DVD/CD Writer
Operating System Microsoft Windows 10 Home OEM (64-bit)
Wireless Network Adapter TP-Link TL-WN881ND 802.11b/g/n PCI-Express x1 Wi-Fi Adapter
Monitor 3 X Samsung S22C200B 21.5" Monitor (or LG IPS 22 22MP57VQ)
....but the MOBO doesn't support SLI so I suppose I can't add 2 GT720....