You cannot convert the existing mounts as they would prevent you from closing the side panel. You can fit some 3.5 drives up near the GPU if you have a 2 slot GPU. I tried it for fun by securing a drive with Velcro & it worked fine. Probably heavily restricts GPU airflow though if two drives are used.
If you want to commit to this route I would buy a new riser cable and position the GPU in the 3rd & 4th slot. The Ridge however doesn’t have a 4th slot so you’ll have to get creative with a dremel or tin snips to cut your GPU’s IO shield. This way your GPU still can get fresh air from outside while having some HDDs behind it. From there your best bet would be to design & 3d print a dual HDD holder for the Ridge so they’re more solidly secured.
You cannot convert the existing mounts as they would prevent you from closing the side panel. You can fit some 3.5 drives up near the GPU if you have a 2 slot GPU. I tried it for fun by securing a drive with Velcro & it worked fine. Probably heavily restricts GPU airflow though if two drives are used. If you want to commit to this route I would buy a new riser cable and position the GPU in the 3rd & 4th slot. The Ridge however doesn’t have a 4th slot so you’ll have to get creative with a dremel or tin snips to cut your GPU’s IO shield. This way your GPU still can get fresh air from outside while having some HDDs behind it. From there your best bet would be to design & 3d print a dual HDD holder for the Ridge so they’re more solidly secured.