Tomb Raider Running smoothly at half speed (AMD Radeon)

[lanczer]

Just got the new tomb raider and have been playing it for a while but im getting this weird performance issue on one of my computers. my desktop is running the game smoothly (between 40-60 fps) but all the animations and controls are at half speed. so for instance when she runs its like shes running on the moon. the weird thing is it does this regardless of settings (ive tried everything between low to ultra, full screen and windowed) when doing research no one else seems to have this issue and all i can find is discussions on nvidea cards.
desktop specs:
i7-3770k
AMD Radeon saphire 7870 oc edition
128gb kingston hyperx ssd
1tb hdd
intel DZ77GAL-70K mobo

when running the game on my laptop (nvidea gt650m) it runs as it should, so i can play it on high setting but maxed out i get low fps. ive tried multiple steps to fix the problem on my desktop including
-clean update to latest driver + roll back to original drive that came with card
-fully updated windows and bios
-launching game from clean boot (no other programs to interfere)
-reverting the stock overclock down to reference card speed

Notes:
-temps are not a problem as it will happen with a completely cool machine
-the [physical] desktop is completely clean as its a relatively new build (not a spec of dust)

If anyone has any suggestions it would be much appreciated as i am completely stumped. or even if anyone else is having this issue as well.
Thanks!

 

[Philhalo66]

try reinstalling the game