Comment 143 for bug 1870736

sudo add-apt-repository ppa:ci-train-ppa-service/4112
worked for me.
GTX 750Ti, 440 driver

-- Logs begin at Mon 2020-07-06 19:24:15 CST. --
7月 06 20:12:56 lixinrui-ubuntu gnome-shell[1095]: Setting screen size 1440x900
7月 06 20:12:57 lixinrui-ubuntu gnome-shell[1095]: Unset XDG_SESSION_ID, getCurrentSessionProxy() called outside a user session. Asking logind directly.
7月 06 20:12:57 lixinrui-ubuntu gnome-shell[1095]: Will monitor session c1
7月 06 20:12:58 lixinrui-ubuntu gnome-shell[1095]: Error looking up permission: GDBus.Error:org.freedesktop.portal.Error.NotFound: No entry for geolocation
7月 06 20:12:59 lixinrui-ubuntu gnome-shell[1095]: JS WARNING: [resource:///org/gnome/shell/ui/layout.js 24]: reference to undefined property "MetaWindowX11"
7月 06 20:12:59 lixinrui-ubuntu gnome-shell[1095]: Getting invalid resource scale property
7月 06 20:13:00 lixinrui-ubuntu gnome-shell[1095]: Registering session with GDM
7月 06 20:13:04 lixinrui-ubuntu gnome-shell[1614]: Enabling experimental feature 'x11-randr-fractional-scaling'
7月 06 20:13:04 lixinrui-ubuntu gnome-shell[1614]: Setting screen size 1440x900
7月 06 20:13:05 lixinrui-ubuntu gnome-shell[1614]: Unset XDG_SESSION_ID, getCurrentSessionProxy() called outside a user session. Asking logind directly.
7月 06 20:13:05 lixinrui-ubuntu gnome-shell[1614]: Will monitor session 2
7月 06 20:13:05 lixinrui-ubuntu gnome-shell[1614]: Telepathy is not available, chat integration will be disabled.
7月 06 20:13:06 lixinrui-ubuntu gnome-shell[1614]: Error looking up permission: GDBus.Error:org.freedesktop.portal.Error.NotFound: No entry for geolocation
7月 06 20:13:08 lixinrui-ubuntu gnome-shell[1614]: Window manager warning: Overwriting existing binding of keysym 31 with keysym 31 (keycode a).
7月 06 20:13:08 lixinrui-ubuntu gnome-shell[1614]: Window manager warning: Overwriting existing binding of keysym 32 with keysym 32 (keycode b).
7月 06 20:13:08 lixinrui-ubuntu gnome-shell[1614]: Window manager warning: Overwriting existing binding of keysym 33 with keysym 33 (keycode c).
7月 06 20:13:08 lixinrui-ubuntu gnome-shell[1614]: Window manager warning: Overwriting existing binding of keysym 34 with keysym 34 (keycode d).
7月 06 20:13:08 lixinrui-ubuntu gnome-shell[1614]: Window manager warning: Overwriting existing binding of keysym 35 with keysym 35 (keycode e).
7月 06 20:13:08 lixinrui-ubuntu gnome-shell[1614]: Window manager warning: Overwriting existing binding of keysym 36 with keysym 36 (keycode f).
7月 06 20:13:08 lixinrui-ubuntu gnome-shell[1614]: Window manager warning: Overwriting existing binding of keysym 37 with keysym 37 (keycode 10).
7月 06 20:13:08 lixinrui-ubuntu gnome-shell[1614]: Window manager warning: Overwriting existing binding of keysym 38 with keysym 38 (keycode 11).
7月 06 20:13:08 lixinrui-ubuntu gnome-shell[1614]: Window manager warning: Overwriting existing binding of keysym 39 with keysym 39 (keycode 12).
7月 06 20:13:09 lixinrui-ubuntu gnome-shell[1614]: GNOME Shell started at Mon Jul 06 2020 20:13:06 GMT+0800 (CST)
7月 06 20:13:09 lixinrui-ubuntu gnome-shell[1614]: Registering session with GDM
7月 06 20:13:16 lixinrui-ubuntu gnome-shell[1614]: GOt configuration change [(0, 0, 1.25, uint32 0, true, [('DVI-I-0', '1440x900@59.606285095214844', {'underscanning': <false>})])]
7月 06 20:13:16 lixinrui-ubuntu gnome-shell[1614]: GOt configuration change [(0, 0, 1.25, uint32 0, true, [('DVI-I-0', '1440x900@59.606285095214844', {'underscanning': <false>})])]
7月 06 20:13:16 lixinrui-ubuntu gnome-shell[1614]: GOt configuration change [(0, 0, 1.25, uint32 0, true, [('DVI-I-0', '1440x900@59.606285095214844', {'underscanning': <false>})])]
7月 06 20:13:17 lixinrui-ubuntu gnome-shell[1614]: GOt configuration change [(0, 0, 1.25, uint32 0, true, [('DVI-I-0', '1440x900@59.606285095214844', {'underscanning': <false>})])]
7月 06 20:13:17 lixinrui-ubuntu gnome-shell[1614]: Crtc at 0.000000x0.000000 size 1152.000000x720.000000 (@ 1.250000 - adapted 2.000000) considering it of 2304.000000x1440.000000
7月 06 20:13:17 lixinrui-ubuntu gnome-shell[1614]: Setting screen size 2304x1440
7月 06 20:13:17 lixinrui-ubuntu gnome-shell[1614]: Setting screen size to 2304x1440
7月 06 20:13:17 lixinrui-ubuntu gnome-shell[1614]: Scaling at 0.625000 (transformation matrix is 104857 = 1.599991) using filter good
7月 06 20:13:17 lixinrui-ubuntu gnome-shell[1614]: Configuring CRTC 441 with mode 446 (1440 x 900 @ 59.606285) at position 0, 0 and transform 0
7月 06 20:13:17 lixinrui-ubuntu gnome-shell[1614]: Setting UBUNTU crtc config crtc 441, timestamp 0 (config timestamp 15166), x: 0, y: 0, mode: 446, rotation 1, n_outputs 1: RETURN reply 0x557d7bfc8000, error: (nil)
7月 06 20:13:17 lixinrui-ubuntu gnome-shell[1614]: Setting screen size 2304x1440
7月 06 20:13:17 lixinrui-ubuntu gnome-shell[1614]: Setting screen size 2304x1440
7月 06 20:13:17 lixinrui-ubuntu gnome-shell[1614]: Window manager warning: Overwriting existing binding of keysym 31 with keysym 31 (keycode a).