Given your situation— 70% overall in 12th , but less than 60% in PCM , and aiming for B.Tech in Computer Science —here are your best options:

Some government engineering colleges may accept students with lower PCM percentages through management quota or direct admission . However, these options often come with higher fees.
Private institutions often have more flexible admission criteria and may offer better placement opportunities.

1. Rajiv Gandhi Institute of Petroleum Technology (RGIPT), Amethi

2. Harcourt Butler Technical University (HBTU), Kanpur

3. Madan Mohan Malaviya University of Technology (MMMUT), Gorakhpur

For more information , you can refer to the following resources:

• 11 Cheapest Colleges to Study B.Tech in India