[CentOS] A query on graphic console

I'm only getting a text console with CentOS-7.2
on my (oldish) HP MicroServer.

The only explicit error I see in Xorg.0.log
is that no driver is found for my Pixart USB optical mouse.

My query is: would that be sufficient
to prevent a graphic console?

Incidentally, I can use X apps, eg xpdf,
if I ssh in from my laptop.

As always, any advice gratefully received.

-- 
Timothy Murphy  
gayleard /at/ eircom.net
School of Mathematics, Trinity College, Dublin