Nice adaptation. Not only does this provide strain relief, it looks tidy.
All these 'compact' PCB cards w/ multi-slot coolers leave the power connector in a terrible location.
Cable-management aside, the proximity to the side panel (in most cases) necessitates putting some strain and angle on the cable+plug. This design completely alleviates that.
As long as you're using a trustworthy adapter, (short) extension, or have a modular PSU, this wouldn't (much) hinder un/re-installation.
I like it.
BTW, this particular model uses a single Tried-and-True (150W) 8-Pin Plug.