How its not for gaming? it has crossfire feature and other things especially for games !
Because as I said before, it doesn't have much power. Very slow memory interface and very few USPs.
Edit:if i want a gaming graphics what should i get for a small desktop cuz the
HD 7870 has a large PCI i want something that can fit like 5450
You're going to have to upgrade the entire machine. For playing heavy graphics games such as Crysis then you will be looking at at least $800.
AMD FX-8350 w/ Corsair H105, ASUS Sabertooth 990FX Gen3/R2, 8GiB G.SKILL DDR3-2133, XFX HD 7970, 512GB Vertex 4, 256GB Vector, 240GB Agility 3, Creative X-Fi Titanium w/ Creative Gigaworks S750, SeaSonic X750, Corsair C70, HP ZR2440w, Win 7 Ultimate x64