I believe the cause was a prog from Giveawayoftheday.com a photo touch up prog, which refused to work in Windows 8 64bit. I rebooted trying to get it to work.
It took between 10 and 20 minutes.
Horrified, i removed the program, and rebooted. No better.
I reinstalled windows, after trying different things including "repair my computer" which if anything made it worse.
It comes on with the Asus screen (the mobo) and before it was 2 seconds, now its 2-3 MINUTES. Then beeps, goes onto the same Asus - as before, but that lasted say 3-4 seconds, now it's 5 minutes plus. Then onto Windows screen which takes a further 5-10 PLUS minutes whereas before it was seconds.
I reinstalled Windows as I say. Maybe it's got SLIGHTLY faster, but not the 20 seconds maximum it was before. What can I do ?

Oh one other thing. I noticed also that if I leave the PC for a while, I have to reboot the damn thing instead of just moving mouse.
And with the reboot lasting so long....