Does GTX 780 support 144Hz?

Yes, G-sync up to 144Hz is supported on the 780. The 165Hz on the PG279Q is a bit of a compromise anyway. At 144hz it is calibrated for the 4ms response time and has very low input lag. As you increase past 144 it starts to get worse.E

Does GTX 780 have DisplayPort?

NVIDIA is using Samsung K4G20325FD-FC03 GDDR5 memory chips on the GeForce GTX 780. Display outputs include two dual-link DVIs, one HDMI and one DisplayPort 1.2 connector. This video card easily supports 4K resolution monitors and supports up to four monitors concurrently.Kh

What series is the GTX 780?

GeForce 700 series
GTX 780 Ti Founders Edition, the flagship card of the GeForce 700 series of 2013. The GeForce 700 series (stylized as GEFORCE GTX 700 SERIES) is a series of graphics processing units developed by Nvidia.

Is 500W enough for GTX 780?

I would say you should be more than fine at 500 watts with a good one. That said the EVGA 500B isn’t the best quality, you should consider changing it anyway, and in that case you may as well go bigger.