SGD900?
I'm not familiar with this term.
But, for playing some casual gaming like dota 2, battlefield, diablo 3 etc, i'd get at least an i3 3220/ fx 4300(i5 3570k is best but if not oc'ing, a 3450 would do), and a radeon 7850/ gtx 650 boost (regular gtx 650/ti are really slow by comparison) or above. A 7770, 650 would do, but only on high ~ 30 to 40 fps. If that's plenty, feel free to head that route.