GT640 boots to random snow display

My Nvidia GT-640 often (maybe 30% of time) boots up (from power down condition) in a strange way on my i7-920 system (no overclock). My primary monitor comes up as a random noise "snow" display. The Windows login graphics are faintly visible under the noise, but it is almost impossible to use the mouse to log in or reboot. The second monitor comes up fine with a normal (blank) Windows desktop. The system always seems to reboot correctly as long as the power stays on. I.e., the problem shows up after power down, then power up -- cold start.

If I then use the PC reset button, the system always (?) boots up correctly. So it seems that sometimes the "power on reset" for the GT-640 is not truly resetting the hardware as it should. (Yes, I could switch the display ports, but then I'd still need to reboot to get both monitors correct.)

The BIOS startup displays normally. I only see the problem when Windows starts.

Is this a known issue? Any workarounds or fixes? TIA!

Tried all this (well, mostly), but the problem continues -- now on Win 10. I am using both DV ports, but not the HDMI port. By the way, the same problems exist when I boot up into Ubuntu Linux - so this seems like a hardware issue, or maybe firmware?

The displayed pattern is like TV snow on top of a faint (correct) windows desktop image. The snow is "alive" -- random in time. In electrical terms, it's like there's an invalid input multiplexor setting -- tristate, or some such.