I know you've probably already checked this, but the only time I've seen all of the symptoms that you?re describing is when there is a loose or intermittent connection between the video card and the monitor.
When you tried the different monitor was it using a different cable?
Is there a DVI to VGA adaptor connected to the video card? If so have you tried using a different one?
To me, a bad PCI-E connector on your motherboard would show garbage on your screen if anything.
Other than that, I'm out of suggestions.
When you tried the different monitor was it using a different cable?
Is there a DVI to VGA adaptor connected to the video card? If so have you tried using a different one?
To me, a bad PCI-E connector on your motherboard would show garbage on your screen if anything.
Other than that, I'm out of suggestions.