We study the identity testing problem for depth 3 arithmetic circuits (\Sigma\Pi\Sigma circuit). We give the first deterministic polynomial time identity test for \Sigma\Pi\Sigma circuits with bounded top fanin. We also show that the rank of a minimal and simple \Sigma\Pi\Sigma circuit with bounded top fanin, computing zero, can be unbounded. These results answer the open questions posed by Klivans-Spielman [KS01] and Dvir-Shpilka [DS05].