It was the year 1996 and the first real 3D accelerator appeared on the market. It was called Voodoo. It technically wasn't the first and many other claimed to support 3D, but this was specialized for3D computing. And that was quite strange at that time.
3Dfx Voodoo 2 - source WikiMedia Commons
While others tried to combined 2D and 3D graphics cards into a single card, 3Dfx took a very different route. You took your regular card and slotted it into the Voodoo card. It came with many issue and a lot of people didn't do it correctly, but whoever managed to connect everything correctly - he immediately saw the differences. It's hard to describe, maybe the closest feeling today is trying out VR - so big was the difference at the time. Specially in FPS and racing games that supported this graphics cards, the view was just completely different. Although - many would argue (from today POV) that is still looked like crap.
nVidia Riva 128 - source WikiMedia Commons
There was a time when everybody thought that this was the pinnacle of graphical acceleration, but then the nVidia Riva 128 came and started a fight that pretty much is happening to this day. Some of the fighters changed in that time, but it's still the same fight.