Your own external mark is more important than your internal mark. Theoretically half your HSC mark should be 90 and the other half should be your own. But the system is more complicated than that. If you get a comparatively higher mark in externals than your cohort, your internal mark will be affected. For example, I accelerated business studies last year. By HSC time I was ranked 3rd internally. I did well in the HSC exam and got an external of 94. I received 94 for both internal and external despite the 3rd highest mark being around 92.