Changing monitor resolution on 12.04

[Jim Byrnes]

On 12/13/2012 10:31 AM, Liam Proven wrote:
> On 13 December 2012 16:23, Jim Byrnes <jf_byrnes at comcast.net> wrote:
>> On 12/12/2012 12:31 PM, James wrote:
>>
>> You seem to be on kde, I am on Unity/Gnome and don't seem to have a Xstartup
>> file.
>>
>> This got me thinking.  I have a perfectly working twinview setup on 10.004.
>> I just compared the two xorg.conf files. The 10.04 one has references to two
>> monitors and screens and the 12.04 one refers to only one.  I wonder if it
>> is as simple as copying the 10.04 xorg.conf to 12.04?  Probably not but I
>> think I will give it a try later.
>
> Just an FYI.
>
> I recently installed 12.10 on my PC. New machine but with the nVidia
> GeForce 230 from my old PC installed. I'm not a gamer but I use
> dualhead; it may not be the fastest but it does all I need and more.

Neither am I.  The same equipment was easy to setup and worked just fine 
under 10.04.

> On 12.04 my setup - identical twin Dell D1626HT 21" CRTs - worked
> fine, with both at 1600×1200 at 85Hz.
>
> On 12.10 this was not possible. Much experimenting - including xrandr
> - revealed that the nVidia driver would not permit me to set this res
> on my right-hand screen.
>
> The reason was that the LHS VDU was connected via a DVI-VGA adaptor
> and VGA-VGA cable. The RHS one was on a DVI-VGA then a VGA-BNC cable
> with separate R/G/B/v-sync/h-sync cables. This gives a better picture.
>
> The thing is, a BNC cable does not transmit monitor information back
> to the PC - this is called EDID data.
> http://en.wikipedia.org/wiki/EDID

My system has vga and dvi connections. The left hand monitor is an HP 
with a hdmi & vga connections. It is hooked up using a dvi to hdmi 
adapter and it is the monitor that is recognized at 1920x1080 resolution 
by the driver.  The right hand monitor is a Hannspree. It is hooked up 
vga to vga. It is the one that under 10.04 could achieve 1920x1080 but 
under 12.04 cannot.

I did find one possible solution that involved EDID. I tried to follow 
along with what he was doing, but frankly the whole thing made my head 
hurt so I started to look for a simpler solution.  I'll to find it again 
and try to understand it this time

> Without it, the driver didn't know what screen I had and would not
> allow anything over 800×600 at 60Hz - playing it very safe for almost
> any monitor from this century.
>
> It's not Ubuntu's fault (tho' Ubuntu's monitor selection tools are
> pathetic.) It's the nVidia driver being overly cautious.
>
> My workaround was to switch to a VGA-VGA cable.
>
> I cannot suggest anything for you, but I am pointing at the nVidia
> driver and saying "j'accuse."
>

Thanks for the info.  I seems to suggest that simply swapping xorg.conf 
files is not going to help but I guess I'll give it a try.

Is there a way to revert back to the driver used in 10.04?

Regards,  Jim