Computers --> Asus --> Intel this will be best but you have only one main category that is Computers then use this Asus --> Intel because you can add the Computers category anytime and then shift to other categories into it which is an easy process. Need reindex not more than that but yes it might impact on SEO if not properly handle
It would be recommended that the products have the complete path:
root category - category - subcategory - subcategory of subcategory
This thing also helps on the SEO side. For example, if a customer accesses the 'Computers' category, he should automatically see all 'Computers' products, whatever their model. You can use the brand (example Asus) ...