Please attach (as opposed to paste) the full Xorg.0.log file for both cases.

Created attachment 11289 [details]
log with the new driver

Created attachment 11298 [details]
log with the old 6.6.193 driver

Does restricting the maximum virtual size using

        Virtual 1400 1050

in SubSection "Display" help?

I had
Virtual 2048 2048
for a bit, (think i read it on think-wiki) and it did not change anything. I will install the 6.7 driver again and try sometime soon and report back with it set at  1400 1050

(In reply to comment #4)
> Does restricting the maximum virtual size using
> 
>         Virtual 1400 1050
> 
> in SubSection "Display" help?
> 

Yes, that fixed it for me, thanks!

So the default maximum virtual size seems to use up too much video RAM for you.

I've reduced the default sizes in git a bit.  I haven't had a chance to look into any alternative options yet.