Hi,
If you find the price diference to be really small, the X will be better binned, which mean it should boost higher with less voltage and so it should run cooler.
And the X got a better stock cooler.
On the other hand the diference in performance, when you use the same cooler, is close to non-existance.
I said get the best priced one, if the diference is small I would get the X, if not, just get the non-X and maybe later you can upgrade its cooler and get the same performance as the X.