When I said daft I meant it as a joke, you don't need to take dust filters out, let alone the top cover.
The temps you are seeing are not normal for the airflow you have, the problem is not the case.
An MSI 6G user, on on another forum, posted the temp with his card (after 15 minutes of unigine heaven in loop like mine).
At stock his card get 76°c at 73% fan speed.
I have the impression that the top fans are smothered by the cover... the grid on it is dense and the distance from the fans isn't optimal.
I'm thinking to change side 200mm fan with a pair 140mm fans, more "aggressive", to push more fresh air and push out more hot air... would you recommend it to me?