You need to clear GATE first as GATE is one such exam, where ones technical and general aptitude is tested. Today, more than 2000 jobs are available for a fresh graduate in engineering in major PSUs in India. The list includes IOCL BHEL , NTPC , BPCL , CEL Power Grid and likes.

All these Public sector companies recruit Engineer Trainee (ET) based on the GATE scores. Initially they would shortlist candidates based on GATE scores and then the process is followed by GD and Interview for assessment of different facets of knowledge. So for psu go for gate first .