Sound latency issue

ok, bit of a random one here, had an asus 7970 running happily on win10 upgrade, I got offered an asus 980 strix at a nice price so decided the upgrade might be worth it.
but now the sound is distorted and choppy, sounds like a latency issue. I correctly uninstalled anything and everything amd installed the card, the NVidia drivers and that’s the only thing I have changed, I get it on bf4 campaign bf4 normal, wow, even on youtube “IF” I have a game open. if I minimize wow for example the sound improves, but open it up in normal or windowed its horrid, it does sometimes sort itself out but takes a while.
any ideas ? have reinstalled drivers left right and centre, just about anything …
spec is…
i5 3570k
asus p8z77-v
850w psu
triton pro+ on optical out
asus 980 strix
16gb 2133 ddr 3
anything is welcomed…
thanks in advance