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Page 1 of 8  Last few months rumors about new redesigned ATI’s GPU that should replace HD4870 were appearing on regular bases. Reason is simple: price for GeForce GTX260 has dropped significantly so, logically, HD4870 has to follow the same trend to keep up the pace. Of course when something like this happens, very often “a gap” in product lineup is created because price for HD4870X2 hasn’t change significantly. Since ATI’s single GPU high-end graphics card operates at relatively high 750MHz, it is obvious that without redesign in GPU architecture higher frequencies and performance levels cannot be achieved. ATI tackled this problem differently from its previous practice.
GPU that is present on HD4890 (RV790) is very similar to GPU found on HD4870 (RV770) because both share same number of transistors (956 million) and same manufacturing process: 55nm. Of course modifications are present in form of Steam Processor optimizations that are now more power efficient and with significantly lower heat emission. This resulted in potentially higher GPU frequency that can be achieved. While RV770 (HD4870) approached overclock margin around 800MHz, new RV790 achieves same frequency with ease. It is very important to point out that this increase in frequency isn’t marginal success but real performance increase in form of 100MHz and higher frequency which is more than 10% more than predecessor. This, of course, promises higher overclock margin but more about that later. Of course ATI has also improved memory bandwidth by using memory chips with lower latency and higher frequency.
Packaging
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Radeon HD4890 that arrived in our test lab is signed by PowerColor and presents classical referent design with customized sticker on cooler. Packaging is, typically for PowerColor, without too much additional accessories and in mid-size format. Manufacturer provided, in the box, disk with drivers, all necessary cables, DVI-VGA and DVI-HDMI converters together with manual. This graphics card has well known cooling solution that was used on most HD4870 models . This means that noise that “blower” fan will generate for speeds above 50% (around 2000RPM) of maximum RPM, will be almost intolerable. Everything above this RPM value will result in noise levels that can be suppressed only by increasing volume on speakers or by using headphones. Luckily this will occur rarely in case you don’t plan extreme overclock of this graphics card.
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For “casual” overclockers values around 40% of maximum RPM will do just fine and noise will be hardly noticeable. This battle-hardened veteran cooling solution is very reliable and trustworthy but we hope that some manufacturers will create their custom cooling solutions with better performances. PCB on this graphics card is, as expected, red colored. It holds RV790 chip (that has slightly larger die size than RV770) and GDDR5 memory chips. These memory chips have even bigger frequency gains than GPU because they have for 175MHz higher frequency (700MHz effectively because multiplier is 4 for GDDR5) which is 20% frequency increase.
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Graphics cards 
