I wonder if you need the 890x chipset unless you want all the bells and whistles of SATA 3 and USB 3. If you do then thats fine, if not save yourself some money and take a look at lower range chipsets.
Also Physx is pointless really, there's no point actually going out of your way in getting a dedicated physx card, you may as well turn it off and turn some other settings up to compensate.
Also you're better off running 4GB (2x2GB) RAM in dual channel rather than 6GB (3x2GB, i'm assuming) of RAM in single channel. You will get better performance benefits out of dual channel and you won't even miss the 2GB difference as you're only really gaming.
You say you need UATX, then the only option there is the Gigabyte one as the MSI one is full ATX as far as i can see.
Have a look for an Asus board and see what they offer, i always prefer them overall.