I have changed config in the following way:
overscan_left=16 overscan_right=16 overscan_top=16 overscan_bottom=16 framebuffer_width=800 framebuffer_height=600 config_hdmi_boost=6
And I am in text mode (no GUI).
With this I have TV blinking with period of several seconds.
Also the TV reports 640x480 on it's
OSD, despite the fact I see by eyes, that resolution is larger, then when I leave
framebuffer lines commented. When these lines commented, the
TV is still blinking.
What else can be done?