Unfortunately, aforementioned PCB's have not produced any meaningful result. The fact that the PCB's only consist of a handful of parts, which have everything integrated inside, means I can't really do anything to fix it - most likely there are high-frequency signal problems, which are though to fix without very (very) expensive scopes!

So I have decided to give up on this direction, and try something new.

It will no longer be a "DVI sync extractor", but a "monitor sync extractor"; in other words, I will try to look inside my monitor and find a V-Sync signal somewhere on the monitor's PCB! That means this project failed as a generic project, but hardcore hackers might still find it useful as an example for doing the same to their own monitors.

Stay tuned! :)