Platform Trends: Budget GPUs Galore

Sure, AMD and Nvidia have fast, fire-breathing graphics cards, but the rivals are now tempting bargain hunters. How do these strategies stack up against each other -- or against price cuts on last year's cards?
Posted September 12, 2008

Vince Freeman

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The loudest buzz in the PC graphics market is usually about Nvidia's and AMD/ATI's latest ultra-high-end products -- cards with graphics processing units (GPUs) strong enough to whip any game on the market, more onboard memory than your current desktop, and power requirements that could shut down the grid. But what about the rest of us, who may not require enough graphics horsepower to render the next Pixar movie? Well, Nvidia thinks it has the answer with a new entry-level offering, while AMD is making do with motherboard graphics while waiting for the next Radeon HD 4000 wave to hit.

Low, Low Prices!

Nvidia has been constantly fine-tuning its GeForce 9 Series, adding new cards, rebranding others, and plugging various gaps in its lineup. Now, not long after the July debut of the value-priced GeForce 9500 GT, comes the even more economical GeForce 9400 GT, a card designed to offer DirectX 10 goodness for less than $60.

The GeForce 9400 GT graphics processing unit is based on the same 55-nanometer-process G96 core as the GeForce 9500 GT, but with some architectural changes. For starters, the stream processor count has been cut in half, down to 16 from 32. That cuts GPU performance in half, even with clock speeds matching the older card at 550MHz core and 1400MHz shader.

To keep costs low, Nvidia's reference specification also calls for low-end DDR2 memory, running at an 800MHz effective speed. Memory architecture is also decidedly entry-level, with a 128-bit link to the onboard DDR2 for a meager 12.8GB/sec of memory bandwidth. Memory capacity, on the other hand, is actually above average for an entry-level card, with a default of 512MB that can be doubled to 1GB at vendors' discretion.

This sounds a lot like a rebadged, overclocked, slightly enhanced 55-nanometer version of the old GeForce 8500 GT, and it likely is, but these are only the base specifications. As with all GeForce cards, vendors are free to tweak the design and offer higher-clocked versions depending on market demand. Power and thermal specifications are nominal, with the GeForce 9400 GT sporting a maximum power rating of 50 watts -- low enough for even a humble 300-watt desktop PC power supply -- and a maximum GPU temperature of 105 degrees C.

On the feature side, the GeForce 9400 GT is a full-fledged PCI Express 2.0 card, supporting features such as Nvidia's PureVideo HD playback, PhysX game physics, CUDA programming interface, and DirectX 10/OpenGL 2.1.

AMD Pushes its 790GX

Meanwhile, while AMD has not officially launched a low-end member of its Radeon HD 4000 line, the company has put the integrated graphics segment in its sights. The AMD 790GX motherboard chipset is a higher-end version of the 780G, which incorporates the feature set and performance of the previous 790X while offering integrated graphics on a HyperTransport 3.0 Socket AM2+ platform. Moreover, the 790GX doesn't suffer the higher-clocked Phenom jitters that the 780G did, and can handle the company's entire desktop processor line right up to the 140-watt Phenom 9950 Black Edition.

The main feature of the 790GX chipset is of course its graphics -- an onboard version of the Radeon HD 3300 GPU, stepping up from the HD 3200 platform of the AMD 780G. This is a fully DirectX 10.1-compatible graphics core, with a clock speed of 700MHz versus 500MHz for the 780G.

The 790GX makes use of onboard DDR2 memory for framebuffer and textures, utilizing the motherboard's DDR2-800MHz speeds and the HyperTransport 3.0 architecture. As always, using system memory does limit performance compared to a discrete graphics solution, but the 200MHz increase in core clock speed is still significant: The HD 3300 has now leaped past the 600MHz Radeon HD 3450 card in GPU power and real-world gaming performance, so the 3300 label is a bit of a misnomer.

But that's not the end of the story, as the AMD 790GX adds another neat trick by incorporating onboard display cache or sideport memory. The high-end 790GX configurations include 128MB of onboard DDR3, which can yield up to a 15-percent jump in gaming frame rates. In short, the strategy is not only to provide the top integrated graphics solution but to outperform entry-level dedicated graphics cards.

The 790GX also supports Hybrid Graphics technology, which allows the onboard GPU to team up with a dedicated Radeon HD 2400, 3450, or 3470 card in CrossFire mode. Both the optional DDR3 buffer and CrossFire support deliver real-world benefits, with a noticeable jump in gaming benchmarks when both features are enabled.

The Approaching HD 4000 Wave

So far we've covered the present, but September is expected to see perhaps the biggest entry-level splash yet: While AMD has already unveiled the high end of its ATI Radeon HD 4000 series, the Radeon HD 4650 and 4670 are poised to attack the mainstream -- read GeForce 9600 -- market while two new Radeon 4400 cards strike the segment below.

The Radeon HD 4450 and 4470 will use the same basic GPU, but the base architecture of their upcoming ATI RV710 has come under dispute: Depending on which source you listen to, it could feature 40, 80, or even 120 stream processors. We think 80 sounds about right, with DDR2 memory likely for the Radeon HD 4450 and a GDDR3 option for the HD 4470. Memory bandwidth and overall performance won't be anything outrageous, but should be enough to put Nvidia on the defensive in this price range.

While we do welcome more competition in the entry-level graphics market, this sector is getting pretty crowded and seems to grow larger every month. Part of this is due to newly released sub-$100 products, but mostly it's a combination of accelerated development schedules and the filter-down effect of older mainstream (or even high-end) cards falling off the radar, then reappearing at a fraction of their original price. Repositioned mainstream cards like the GeForce 9600 GSO, GeForce 8800 GS, and Radeon HD 3850 might make life tough for the under-$100 newcomers.

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Tags: programming, Specification, AMD, nVidia, SEC

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