Screw adjustable support to prevent drooping and cracking of the lengthy GPU. The base, nut and screw are generic, the piece that makes contact with the corner of the GPU is likely unique to card mentioned.
Designing new top piece for card you ended up with should be breeze using the FreeCAD file provided - or just use the secret recipe of the square contact piece: 10x10x3, 1mm rounding for corners.
The author marked this model as their own original creation.