GeForce 8400 GS and Radeon HD 3450
Feel free to skip this part if you're au fait with what makes each of the card's tick, but taking the time to read what's presented will provide you with a better understanding of the results you'll see on the upcoming pages.NVIDIA GeForce 8400 GS
The trick in producing a feature-rich, inexpensive discrete graphics card rests with looking at what's offered in the high-end and mid-range spaces and then reducing the transistor and die-space count by lopping off performance-enhancing attributes such as shader counts, memory speeds, and memory-interface width. The guts should be the same, adhering to the same API specification, but it won't be as fast. Pay more and you get more speed, really.
Now, NVIDIA has a strong DX10-compliant line-up across the board (pun intended, folks), ranging from the overblown GeForce 9800 GX2, currently retailing for £350, through to the GeForce 8400 GS, starting at £20. What's crucial to note is that all GeForce 8- and 9-series GPUs emanate from the same progenitor - G80 (GeForce 8800 GTX) - and can thus run the same gaming code, replete with multifarious special effects and image-quality enhancements. Want to run Crysis on a GeForce 8400 GS? It will render the game correctly, but will do so at slide-show speeds unless image-quality and resolution are turned way down.
Completing the picture, and depending upon territory, NVIDIA's partners still sell older SKUs, such as GeForce 6- and 7-series models, and whilst they'll render practically every game available today, the as-yet-unproven benefits of DX10 gaming and hardware-assisted high-definition decode of Blu-ray and HD DVD are missing.
Reference GeForce 8400 GS (code-named G86) cards ship with 16 unified shaders that operate at 900MHz. The eight texture-mapping units and four ROPs run at 450MHz, which is the core speed. Cards can be equipped with either 128MiB or 256MiB of DDR2 memories, which communicate with the GPU via a narrow, 64-bit path. A basic understanding of the specifications informs you know that they're a reasonably fair compromise when reducing retail costs to just £20.
GeForce 8400 GS, released in June 2007, also has NVIDIA's second-generation video-processing engine, VP2. This means that the card helps hardware-accelerate all stages of H.264 decode and most of VC-1: two codecs used in Blu-ray and HD DVD compression. The idea is to minimise the load on the host CPU, leaving it relatively free for other tasks.
ATI Radeon HD 3450
NVIDIA's taken G80 as its architectural base for all present DX10-based cards. ATI's done so with the extant Radeon HD 2900 XT, launched just over a year ago.
ATI GPU-slimming machine took the HD 2900 XT's 320 shaders and reduced them to 40 for the Radeon HD 2400 range, operating at core speed. Four texture-mapping units and four ROPs survived the economic cull, too.
Radeon HD 2400 was released in two flavours - Pro and XT - that were differentiated with respect to core and memory speeds; both shipped with an NVIDIA-matching 64-bit memory bus that connected to either 256MiB or 512MiB of DDR2 or GDDR3 memory.
ATI also had its own video-processing unit, UVD, that hardware-accelerated all facets of the two previously-mentioned codecs.
Further, in a nod to multimedia usage, Radeon HD 2400s were endowed with HDMI pass-through of the motherboard's audio, which, under Vista's UAA, was transported to the DVI port at the back of the card and, via an adapter, out to an HDMI-compliant display, without the need for additional cables.
Earlier this year, ATI introduced the Radeon HD 3400- and 3600-series, to replace the incumbent HD 2400 and 2600s. Retaining the same guts, HD 3000 brought with it a slew of minor benefits, including PCIe 2.0 connectivity; DX10.1 support; 55nm production; wider choice of display outputs; and finer control over the GPUs active state(s).
The Radeon HD 3430/50/70 are distinguished via frequencies alone, and a default-clocked HD 3450 ships with core and shader speeds of 600MHz and an effective memory clock of 1,000MHz. Partners can choose whether to outfit the cards with either 256MiB or 512MiB of RAM, of course.
Throwing that all into a table:
| GPU | ATI Radeon HD 3470 GDDR3 | ATI Radeon HD 3450 DDR2 | ATI Radeon HD 2400 XT GDDR3 | ATI Radeon HD 2400 Pro DDR2 | NVIDIA GeForce 8500 GT | NVIDIA GeForce 8400 GS |
|---|---|---|---|---|---|---|
| API | DX10.1 + SM4.1 | DX10 + SM4.0 | ||||
| Transistors (million) | 181 | 180 | 210 | |||
| Manufacturing process (nm) | 55 | 65 | 80 | |||
| System bus | PCI-Express 2.0 | PCI-Express 1.1 | ||||
| Core speed | 800MHz | 600MHz | 700MHz | 525MHz | 450MHz | 450MHz |
| Texture units | 4 | 8 | ||||
| ROPs | 4 | 4 | ||||
| Fillrate (GTexels/s) | 3.2 | 2.4 | 2.8 | 2.1 | 3.6 | 3.6 |
| Memory speed, effective (MHz) | 1,900 | 1,000 | 1,600 | 800 | 800 | 800 |
| Memory Bus Width (Bits) | 64 | 128 | 64 | |||
| Memory bandwidth (GB/s) | 15.2 | 8 | 12.8 | 6.4 | 12.8 | 6.4 |
| Framebuffer (MiB) | 256/512 | 128/256 | 256/512 | 128/256 | ||
| Stream processing (shader) units | 40 | 16 | ||||
| SP frequency | 800MHz | 600MHz | 700MHz | 450MHz | 900MHz | 900MHz |
| MADD rate (GFLOPs/s) | 64 | 48 | 56 | 36 | 43.2 | 43.2 |
| Video-acceleration technology | Avivo HD (UVD) | PureVideo 2 with VP2 | ||||
| Outputs | 2x
dual-link DVI with HDCP 2x DisplayPort HDTV-Out HDMI |
2x
dual-link DVI with HDCP HDTV-Out HDMI |
Dependent upon AIB | |||
| Expected retail price | £39 | £23 | £33 | £24 | £34 | £20 |
The ATI Radeon HD 3450 and GeForce 8400 GS are reasonably well-matched on the specifications' front, albeit the Radeon ahead bandwidth and pure throughput, but the GeForce jumping out with respect to fillrate.
The HD 3450 sits somewhere inbetween the older Radeon HD 2400 Pro and XT SKUs.
Lastly, the GeForce 8400 GS and SLI-supporting 8500 GT only vary in the memory bus, with the latter employing a 128-bit path for double the memory bandwidth.
