Ive runned cc cleaner, spybot, and ereased the prefs of C6 and reinstalled C6 with the last update.
I ve turned off every process i dindt really need., and almost everything i could, im now with 39 processes. (if im not wrong, cubase opens 4 video process, lots of ram going there…)
gonna try the dpc latency checker, but i already used task mannager everytime i open cubase, as a way to know whats going on in my system.
256 colours is an option in the run app. Right click on mouse, Prop/compatibility/run in 256 colours (and as administrator too!)
I use the Saffire Le firewire driver, that gives me a 5ms output latency (i use my vst instruments for live shows)
Ive unistalled jbridge, and reuse the brige inside cubase. but ive unistalled some pplug ins too, for the problem it cause using those. (i can try using the ones with trouble with the jbrige, perhaps that could work)
Ive got some friends for sure, but no friends with cubase 6.5.4 64 bits./ Only one that purchased the product with me, and is experiencing the same trouble. Video problems seems to be for boths) thats why im asking for help here, and spent like 60 hours in front of my loved vaio computer! 
I will call Yamaha this monday., and see what they say… For me