The PG278Q monitor is certainly a great buy and it's totally worth the money in my opinion. It combines 120/144 Hz with a 1440p resolution, 1ms response time (GtG), G-Sync module and ULMB (LightBoost-like strobe backlight). No other monitor in the market offers this much. Despite being a TN panel, it's a premium 8 bit panel specially made for this monitor, that should approach the color reproduction quality of some IPS panels. And we have to take into account that, as things now stand, no IPS panel can consistently reach the pixel response times of the much faster TN panel. I am also waiting for this monitor, btw.
You won't be able to reach 120 fps on the most recent games at the Ultra setting with a single 780 Ti Matrix. But that's why I think this monitor can last for quite some time before you feel the need to upgrade. We don't have enough juice in any single GPU yet to take full advantage of the monitor. So, in my opinion it presents a great value.
As to the Matrix card, I have that doubt too, but I feel that if you aren't the extreme overclocker guy, there should be no point in getting one (aside from looks). Go grab a DCU II and call it a day.
Haswell-E? 5930K? If it's indeed an 8-core CPU, you'll have a true beast inside your machine.
