Dashes all over screen?

[Tom Horsley]

Out of curiosity I installed Fedora 21 Branched to see if
nouveau supported the GeForce GTX 750 Ti (GM107-A) video
card in 3840x2160 resolution on my Samsung U28D590 UHD
monitor.

It seems to load nouveau, but nouveau decides it doesn't
support this card (I guess), anyway it falls back on VESA,
which winds up powering off the monitor.

When I boot multi-user to just use the console in
text mode, I get lines full of dashes instead of an empty
black background (if I type an x it looks like an *
for instance).

I guess I didn't have a lot of hope for the nouveau driver,
and this video card, but the dashes all over the screen seem
weird enough to mention on the list:-).

Anyone have any clues about that?