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What you can do with 55nm and a gig

Posted by Robert Dow on April 2nd 2009 | Comments Closed
Categories: Hardware Review
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The HD 4890 is a dual-slot solution with two DVI-connectors

FIGURE 1: The HD 4890 compared to its competitors.

ATI announced two new top-of-the line single GPU AIBs this week: the HD 4890 and the HD 4890 OC. Both AIBs are based on the RV790 GPU. The new GPU is a revamped "shrink" version of the RV770, the GPU that powers the HD 4870. The RV790 is built on a 55nm process and it has 959 million transistors. ATI turned up the core clock to 850 MHz in the standard HD 4890 and 900 MHz in the OC version, which represents a 50MHZ and 150MHz increase over the HD 4870. The memory clock, driving 1 GB of GDDR5 memory, was also increased 8% to 975 MHz. As a result of the tweaks, ATI has increased the fill rate of the HD 4890 16% to 13.6 GPixel compared to its RV770
predecessor.

The HD 4890 OC has improved 18% in benchmarking scores over the 1 GB HD 4870.

All HD4890 benchmarking scores were obtained using the HD4890 OC running on an Intel Nehalem platform.

ATI’s new Catalyst Control Center makes it easy to overclock the RV790. ATI added a new tab in the Control Center called “ATI overdrive” which offers the option to overclock the core up to 1000 MHz. ATI recommends a limit of overclocking to 950 MHz, so that’s where we kept it, but there are doubtless going to be users out there who are going to turn it up all the way. We also turned the memory clock up to 1075 MHz. By doing that we gained up to a 10% increase in scores using ATI overdrive.

ATI distributors will be launching both cards, of course, with all different SKUs.

The top of the line Nvidia AIBs still outperform the HD 4870 in some benchmark tests even when they’re overclocked, but considering that the HD 4890 is going to hit the shelves at a price of $229 ($249 for the OC version), compared to the GTX 280 that is running GGD3 and can still cost anywhere between $330 to $350, it will be hard for many, in these times, to justify the extra cost for the increased performance. The HD 4890 also consumes less power. The GTX 280 uses roughly 290 watts compared to the HD 4890’s 190 watts.

The RV790 also offers ATI’s Unified Video Decoder 2 (UVD 2), which ATI says can free up the CPU for other tasks and can even handle the most processing-intensive content, including VC-1, H.264 and now MPEG-2. It can also support Blu-ray functionality with dual-stream, picture in picture (PIP)
capabilities.

ATI is promoting their Stream technology for the HD 4800 as well. The company’s technology can accelerate the conversion of standard and HD video into multiple formats for use on different consumer electronics devices. ATI’s Video Converter, designed to enable GPU transcoding of HD video streams, is currently available.

And, with DVD upscaling, users can watch standard DVD movies in near high-definition quality. The GPU uses post-processing algorithms to enhance standard and low resolution videos and movies on an HD display.

ATI has also introduced Dynamic Contrast that automatically adjusts the contrast and brightness during scenes to consistently deliver a crisp, vibrant picture.

What do we think?

We love to see new high-performance graphics AIBs come to market, especially when they are priced under $270. The RV790 is an impressive revamp and given the 20% increase in performance for the price, we expect the board to do very well.—RD