taken from a news site; CNET, that had a article on the Steam Machines:
"860M has 1,306 GFLOPS of FP performance VS PS4 at 1.843 tflops.
860M has 80.2 GB/s of RAM bandwidth VS PS4 at 140.
860M has 40.8 GTexel/s vs 57.6 for PS4" - douglord
That 449$ model of the steam machine from Alienware is probably not going to give you the same gameing experiance a PS4 would.