New mode XRANDR not good for KDE

Upgrading an old desktop computer with an old NVIDIA graphic card ( Geforce 6150 ), I had the disageable surprise
to discover that the nouveau driver which worked fined with Slack 14.2 and a 4.x kernel does not work with Slack 15 and a 5.x kernel !

I tried to compile proprietary NVIDIA drivers but all of these failed to compile ( the 304 version that fits with the card or the 536 new one)

So I had the only choice to have a VESA driver.

But when selecting VESA driver, I only obtain poor resolution : typically 1024 x 768 for a screen ( BENQ FP202W) thac can handle up to
1680 x 1050 at 60 Hz.

I decided to create a new resolution with these characterics

First, I created a new Modeline using cvt or gtf and put in xorg.conf

Then, I give this modeline to xrandr using

Code:xrandr --newmode "1680x1050" 146.25 1680 1784 1960 2240 1050 1053 1059 1089 -hsync +vsyncFinally I add this new mode to the xrandr list :

Code:xrandr --addmode default 1680x1050Looking at the list of resolutions stored in xrandr, I see the 1680x1050 mode but displayed with the frequency ( 59.95 )
while the other resolutions are displayed with a 0.00 frequency.

Nevertheless, I open the Display Configuration Window in KDE and see all the resolutions displayed including the 1680x1050

But, when I select it, even if the display in the window is right , I get an error and the resolution is not selected !

I also tried to display it with xrandr by

Code:xrandr --output default -- mode 1680x1050but here I get a CVCT error

So what is wrong ? Is it the frequency 59.95 in xrandr which is not correct ?

Any idea will be welcomed
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