Which PCIe Slot is best for your Graphics Card?
The EVGA GT 1030 SC Single Slot Graphics Card is an example of a modern single slot GPU on the market, and with this particular GPU it actually has "single slot" in its actual model name.
AMD Radeon Pro W7600 8GB 130W Single Slot GPU Launched
The AMD Radeon Pro W7600 is a new single-slot 130W GPU designed to bring new features to the lower-cost professional graphics market
GIGABYTE AORUS RTX 3070 MASTER Specs | TechPowerUp GPU Database
You also have 2-slot and 2.75-slot GPU coolers, differing power phase designs, single or dual BIOS options, different trim colors and more.