Crossfiring R7 240 and 250x

[Duelas]

Hi everybody!
I am here to ask if it is viable to crossfire a 240 and a 250x

my mobo is asus a88xmplus which have a pcie3.0 x16 and a pcie2.0 x16 (x4 mode)
my plan is to put 240 on 2.0 slot and 250x on 3.0 slot
and in order to make a smaller difference between two cards
i will oc the 240 and lower the 250x with the CCC

and the card I m having now is a r7 240 which means I have to buy a 250x to do this.
so I m considering to do this crossfire option (if it is viable) or just simply buy a new card like r9 270

For a reference, I m upgrading this to play AC Unity

 

[renz496]

simply going for 270 will give you less trouble. it is possible to CF the two but usually people only going to do CF (or SLI for nvidia cards) on midrange gpu or faster.