$900 Gaming and can upgrade later

You dont need a 900 watt psu . Even if you added a second 4890 you wouldnt need a 900 watt psu

It also appears to be a fairly cheap 900 watt unit .

Look for something with ACTIVE PCF for better voltage control and stability

Maybe a corsair 750 tx if you want a second gfx card , or a 650 if you dont