ATi (later bought by AMD) released GPUs with series designations in this order:
- Wonder
- Mach
- Rage
- Radeon 7000
- Radeon 8000
- Radeon 9000
- Radeon X300, X500, X700
- Radeon X1000 (Shortly after, ATi was bought by AMD)
- Radeon HD 2000
- Radeon HD 3000
- Radeon HD 4000
- Radeon HD 5000
- Radeon 6000 (Current series)
- Radeon 7000 (Due in a few weeks to months)
NVIDIA has an equally long history:
- RIVA
- RIVA TNT
- Vanta
- RIVA TNT2
- GeForce
- GeForce 2
- GeForce 3
- GeForce 4
- GeForce FX 5000
- GeForce 6000
- GeForce 7000
- GeForce 8000
- GeForce 9000
- GeForce GT100 (Rebranded 9000, because GT200 designs were delayed)
- GeForce GT200
- GeForce GT300 (Rebranded GT200s, OEM-only, GT400 was delayed)
- GeForce 400 (The first of the "Fermi" GPUs)
- GeForce 500 (Current series)
Each one of those series is a different
generation of hardware. The GeForce 4 was replaced with GeForce FX, and so on. Except where I've noted, each new generation introduced significant new features.
Both companies follow a fairly predictable pattern:
With AMD GPUs, in the 4-digit designations (3000, 4000, and so on), the second digit indicates which market it's intended for. For example, 5500 is entry-level graphics for the 5000 series, 5700 is mid-range enthusiast, 5900 is high-end enthusiast, and 5300 is meant for very cheap systems.
Likewise, NVIDIA uses the second digit to indicate the market. 580 is high-end enthusiast, 570 is mid-range enthusiast, 550 is entry-level gamer, and anything less is meant for super-cheap and OEM systems.
The third (and sometimes fourth) digit indicates relative performance in its class. A GeForce 465 is an underpowered version of the 470. A Radeon 6970 is a souped-up 6950.
NVIDIA also uses another designation: GS is generally the least powerful design. GTS is usually more powerful than GS, but is intended to be cheap. GT is middle-of-the-road. GTX is generally high-end. It's a separate, but related, designation to the second digit of the model number.
The highest-end GPUs like the Radeon 6990 or the GeForce GTX 590 are actually single-card, multi-GPU configurations. The 6990 is a pair of 6970s on a single card, and likewise, the GTX 590 is a pair of GTX 580s. This is similar to getting a pair of 6970s or GTX580s and using Crossfire (AMD) or SLi (NVIDIA) to slave the cards together for better performance. The difference is that being on a single physical card, the 6990 and GTX590 can get slightly better performance,
and it allows you to go even crazier with multi-GPU configurations.
It gets a bit ridiculous.
Going back to generations, you often see games that require a "DirectX 9c-compatible card" or something like that. What that means is that it's looking for a specific set of features provided by the GPU.
In general:
- DirectX 9 requires any thing newer than the Radeon 9000 series or the GeForce FX 5000 series.
- DirectX 9.0b starts with the Radeon X700 and X800, and the GeForce 6000 series.
- DirectX 9.0c starts with the Radeon X1000 series (but not the X1200) and the GeForce 6000.
- DirectX 10.0 starts with the Radeon HD 2000 series and the GeForce 8000.
- DirectX 10.1 starts with Radeon HD 3000 and the low-end GeForce GT200 (anything below 240), the GT300 (except the GT330), and the GT400 (the whole series). Unfortunately, NVIDIA had a lot of problems getting their new Fermi cards out, and that delayed their DX10.1 support.
- DirectX 11 support starts with the Radeon HD 5000 and the GeForce GT400.
In all cases, actually
using DirectX 10 requires at least Windows Vista. XP is limited to DX9.
OpenGL support is a little trickier to track, but suffice to say most OpenGL games require OpenGL 2.1, which tracked with DirectX 9.0a. OpenGL 3.3 is about the same level as DirectX 10.1, and OpenGL 4.1 and up track with DirectX 11. Newer OpenGL features are only limited on the Mac, before OS X Lion, which are all locked at 2.1. Lion supports 4.2. Windows and Linux have no such limitation.
... I think that's everything.
Check these two links for more details:
http://en.wikipedia.org/wiki/Comparison_of_AMD_graphics_processing_units
http://en.wikipedia.org/wiki/Comparison_of_NVIDIA_graphics_processing_units