It's better to get a laptop. They would ask you to turn your computer around and even below your desk to check the environment. Besides, it's not a good idea to burden yourself with things like computer before such an important exam.
Only about 1 person in 30 can score 170+. It's good to have it as a target, but failing to achieve so doesn't constitute any reason at all not to value your own efforts.
Focus on yourself and your own problem. Only by removing your own obstacle, yo…