hi,

you did not mention your branch name, however you may see that in gate exam syllabus only 10-12 subjects is included, so you do not need to study your full bachelors courses syllabus, however gate and ies is quite different, but if you are preparing for gate , you dont need to separate preparations for ies prelims since it is also mcq type. first of all you need to clear your basic conception of each subjects, then you may follow made easy publications books or gkp or galgotias publications books to follow the questions trends, in ies main exam question are descriptive type , so you need to follow standard books or text books to make answers.