The Gigabyte Radeon HD 4890 GV-R489-1GH is a graphics card based on the ATI Radeon HD 4890 chip that offers stunning value: if you get it at the right price.
Two months ago we looked at Sapphire's rendition of the standard ATI Radeon HD 4890 chip - the Sapphire ATI Radeon HD 4890. Sapphire may have trumped the performance of that card with its new Atomic 4890, but, for mainstream customers, it's the stripped-down and raw 4890 that continues to represent the greater value for money.
In terms of specifications, there's little to choose between the Gigabyte Radeon HD 4890 GV-R489-1GH and the Sapphire. Indeed, to all intents and purposes, the cards are identical. The 4890 is built around the RV790 core, a beefier rendition of the RV770 sitting at the heart of the 4850 and 4870. The 4890 is an extremely efficient chip, partly because it's been built using the 0.55nm manufacturing process. So it remains quite compact in spite of a mass of extra transistors.
The clock speeds of the Gigabyte are identical to those of the standard Sapphire, so you get a core clock of 850MHz and a memory clock of 975MHz. The latter combines with the GDDR5 memory to create an effective memory clock of 3,900MHz - The GDDR3 memory favoured by nVIDIA would only double the memory clock. The 256bit memory bus isn't vast, but this card isn't supposed to be hitting the highest heights, and for its purposes, 256bit is more than enough. 800 Stream Processors are provided, and this copious quantity puts the majority of the nVIDIA models to shame.
DirectX 10.1 is offered rather than the flashier 10.0 supported by nVIDIA products. As it turns out, the extra effects offered by 10.1 are meagre indeed, and there isn't really a great deal out there that makes use of the extra 0.1 designation. Perhaps more significantly (for the future, if not the present) is what all of the ATIs lack - PhysX and CUDA support. Theoretically, the nVIDIA cards that offer these facilities will be better at performing the complex calculations needed to create sophisticated physical effects in games (PhysX), and will have a greater programming versatility (CUDA), but we'll have to wait to see if games programmers really start exploiting these features.
Considering that the Gigabyte card is essentially identical to the Sapphire, would it be a surprise were the cards to offer similar performance? Well, tested using the same system and drivers, the Gigabyte actually turned in a slightly improved showing, beating the Sapphire by a frame across almost every game and resolution. This isn't a significant difference, admittedly, but the Gigabyte can certainly compete with the Sapphire, despite that company's reputation for hitting the highest scores.
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