When talking about 'inverted' that usually means the motherboard is flipped in a non standard orientation. There's multiple cases where that's the layout, the gpu on top with cpu below, or even with the gpu vertical, and the 'back panel' on top.
The best part about the darkbase is its modularity. If you are willing to take the 900 screws out, it'll convert from left-hand window with gpu low, to a right-hand window with gpu high and inverted motherboard.
Best Inverted ATX Case and Inverted Micro-ATX Case. An inverted PC case is a computer case that has an inverse layout design, which means the motherboard and components in it are installed upside down (facing down), which is opposite to the traditional way of mounting components, which is in an...
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These have inverted motherboards, some can be shifted like the darkbase, most cannot.
Psu placement is a whole different question. Most modern cases are bottom mount psu. Depending on the case, that can mean fan up to act as exhaust fan, or fan down and seperate from case airflow.