Computer Science is very broad so the answer will be different depending on what you'd like to focus on. Algorithms, data structures, systems, graphics, networking, more theoretical CS etc.
That said, for algorithms I could recommend CLRS, Dasgupta's Algorithms, Kleinberg's Algorithm Design.
For theoretical CS: Models Of Computation by J. Savage, Sipser's Introduction to the Theory of Computation.
For OS: Computer Systems A Programmer's Perspective by Bryant and O'Hallaron, Operating Systems - Three Easy Pieces by Arpaci-Dusseau.
That said, for algorithms I could recommend CLRS, Dasgupta's Algorithms, Kleinberg's Algorithm Design. For theoretical CS: Models Of Computation by J. Savage, Sipser's Introduction to the Theory of Computation. For OS: Computer Systems A Programmer's Perspective by Bryant and O'Hallaron, Operating Systems - Three Easy Pieces by Arpaci-Dusseau.