This is a side effect of the NVIDIA driver performing an analog load detect on the
display connection, which sometimes unavoidably occurs outside of V‐blank,
resulting in the white line.
Monitors with both connector types (DVI and VGA), report either a DVI or VGA EDID
over the corresponding connector. Occasionally, such a monitor will erroneously report a
VGA EDID over the DVI connector and vice versa. If the NVIDIA driver trusts and uses
the provided erroneous EDID, there will be no display on the monitor.
To prevent this problem, the NVIDIA driver performs an analog load detect to determine
whether the connection is VGA. While every effort is made to perform the analog load
detect during V‐blank, this cannot be guaranteed across all GPUs and systems.