Thanks everyone for the advice. The top / primary slot appears to be accessible and the other 3 will involve removing GPU to get at some of the screws. Not the end of the world, just haven't built or pulled apart a PC since 486, or maybe early Pentium.
I recently purchased a pre built PC. I think it is the Eclipse R90S. Ryzen 9 7900X3D with RTX 4090. ROG STRIX X670E-A motherboard.
I want to add another SSD and all the slots, apart from the top one, M.2_1, are hidden behind the graphics card.
Before I start pulling it apart, can you tell me...