Radeon 9700 Pro, high end from over 10 years ago, had a fillrate of 2600MPixels/s
Let's take a high end graphics card from a few years back, say... GTX 480? A 2010 card? That has a fillrate of 33,600 MPixels/sec.
5x 1920x1080 quads is child's play for any reasonable desktop GPU part. In fact high end cards from 2009 could game at 5760x2160 (that's 6x 1920x1080 displays) off of a single card.
I power 2x 1920x1080 screens off of a NUC and am very happy.