Which rig is better for gaming on 3 monitors

Solution
I tweaked your AMD build a little to include a crossfire compatible mobo for a future upgrade. The new build also has USB 3.0 support and a bigger PSU so you could get that second R9 290. I also gave you a significant upgrade on your CPU. http://pcpartpicker.com/p/CBpZGX Here some of mine own builds for around the same price based around AMD although I would go with GTX 970 for the most bang for your buck. Let me know if you decide to add to your budget. These include the OS btw http://pcpartpicker.com/p/sfY4Jx http://pcpartpicker.com/p/YtK6yc
Honestly, at the resolution you will be running they will be the same since the CPU won't matter much at all. The higher the resolution, the less work is required for the CPU and more work for the GPU. I'd take the intel system myself, but you can overclock the FX chip if you ever want too.
 
I would generally recommend the i5 rig as most games will benefit from a few fast cores rather than a bunch of slower ones. however this difference is really only noticeable at lower resolutions, so on a 3 monitor set up your frame rate's going to be largely dependent on your graphics cards.
 
I tweaked your AMD build a little to include a crossfire compatible mobo for a future upgrade. The new build also has USB 3.0 support and a bigger PSU so you could get that second R9 290. I also gave you a significant upgrade on your CPU. http://pcpartpicker.com/p/CBpZGX Here some of mine own builds for around the same price based around AMD although I would go with GTX 970 for the most bang for your buck. Let me know if you decide to add to your budget. These include the OS btw http://pcpartpicker.com/p/sfY4Jx http://pcpartpicker.com/p/YtK6yc
 
Solution