Thinner: When you 1) want a quieter GPU, 2) are too cheap/lazy to water cool, and 3) have an itx case that can't fit a 2.5 slot card without an unsightly bulge :
Fractal Era ITX Review | Up Close | Cases & Cooling | OC3D Review
Graphics Card Slot Types (GPU Width Differences)
Era ITX — Fractal Design
SilverStone INTRODUCTION:ML08
Graphics Card Slot Types (GPU Width Differences)
Mini Itx Case with 2.5 or 3 Slot GPU : r/sffpc
Lian Li unveils SFF chassis supporting triple slot GPU, 240mm radiator | TechSpot
Lian Li Spinoff Ssupd's Meshlicious Case Is a Versatile, Compact Box for a Modest Collection of Powerful Components | Tom's Hardware
Graphics Card Slot Types (GPU Width Differences)
Jonsbo Unveils the V8 Cuboidal Mini-ITX Case | TechPowerUp
MasterBox NR200P Mini-ITX PC Case | Cooler Master
NZXT H1 Mini-ITX Vertical Case Released - It's Not Just a Case - ThePCEnthusiast
Best Mini ITX Cases 2022 - IGN
Cooler Master MasterBox NR200P White SFF Small Form Factor Mini-ITX Case with Tempered glass or Vented Panel Option, PCI Riser Cable, Triple-slot GPU, Tool-Free and 360 Degree Accessibility - Newegg.com
Cooler Master MasterCase NC100 SFF Small Form Factor 7.9 Liter Case with V650 Gold SFX PSU, GPUs 2.5 slots up to 320mm for Intel NUC 9 Extreme Element - Newegg.com
Jonsbo A4 ITX case comes to market | bit-tech.net
Velka 3 — VELKASE
Jonsbo Unveils the V8 Cuboidal Mini-ITX Case | TechPowerUp