Moving to student forum.
poor attention to perspective.
Perspective is critical in giving 3D projects realism. In fact, perspective is arguably more important than the skill or quality of the artwork itself (to a degree).
This piece, for instance, is rather well done in rendering (aside from the abstract background where the objects live) But your headphones dictate a light source from directly above, while the MAC appears to have lighting from the front. Both objects appear to exist on a slightly different plane, the computer having a vanishing point in the lower mid-left field, while the headphones don’t appear to be effected by any noticeable horizon line.
The computer actually has 2 vanishing points, making the keyboard section look warped.
Being that difficult parts of this illustration are done so nicely, like the headphones, while basic errors have been made elsewhere, like the perspective, leads me to suspect that we’re mostly looking at copy and paste artwork rather than something original.