When waking up my MacBook Pro, the external monitor unpredictably displays "snow flakes"

I can't seem to pinpoint a specific cause for this, but sometimes when I wake my MBP the external screen gets fuzzy, like a TV with no reception, but I can faintly see my desktop behind the noise. If I sleep the display again (with hot corners) and wake it up again it's fine. Anyone know how to fix this?

Solution 1:

I have had the same problem with Maverick (in clamshell mode) / external monitor (Samsung SyncMaster 2443) when I lock my screen and use my bluetooth mouse or keyboard to wake up the computer.

I was able to fix the problem in 2 ways:

• open the lid, login and unplu, replug the external monitor (pretty annoying)
• when the multicolor static shows, press CTRL+SHIFT+Eject as if to lock the computer again, then wake up the computer again and I now have the normal login screen as normal (not ideal but less disruptive solution).

I hope this helps !

Solution 2:

Since the mac engages the graphics card with the same precision each time you wake from sleep, it's likely a timing issue on the monitor. (I loose or noisy cable could have the same effect, but much less likely and you would probably have other issues if that were he case)

Have you seen if you can reduce the number of settings the monitor has to scan on detecting a new signal.

You can test this by power cycling the monitor the next time it happens.