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Note: Last week, for the launch of the HD 4800 series, we took a more in-depth look at the changes introduced in this new generation from ATI. If you'd like to read about these changes, go here.

Impressions

The Diamond Radeon HD 4870 is a big card, with a double-slot cooler, but not as big to the same extent that the recent high-end cards from NVIDIA have been. The HD 4870 is about a half an inch longer than the HD 3870, and a bit heavier in comparison as well. The HD 4870 has very similar dimensions to the HD 2900 XT...actually -- wait a second, it seems the HD 4870 has a bit more in common with the HD 4870 than size alone -- as far as I can tell, they share the exact same cooler, although this cooler is encased in a different plastic shell.

Whether or not is a matter of extreme foresight, or merely saving some money by just sticking with a design that worked, the coolers for the HD 2900 XT and the HD 4870 are basically the same: a copper base sits on the GPU on the center of the card and extends to the bracket. Three medium-sized heat pipes help move the 'GPU's exhaust' out to a six inch bank of aluminum heat fins. A high-speed, many-vaned fan sits on the right side of the card, pushing a stream of air through this bank of fins...and viola: your GPU is cool.

This cooling solution seems sufficient for the regular operation of the HD 4870 in our testing. While perhaps the HD 4850's cooling could have been beefed up just a little bit (the 4850 ran fairly hot), this HD 2900 XT / HD 4870 is effective enough to keep the HD 4870's GPU within reasonable temperature ranges. The fan is also, for the most part, not that loud at all -- when it is manually set to full power, or when the card is powering up, at full force this fan can move a huge amount of air and be very loud in the process; but in standard operation, playing games, at least in our experiences, the fan never needed to spin fast enough make a unreasonable amount of noise.

Three really powerful cards: the XFX 9800GX2, the Diamond HD 4870, and the GTX 280

One thing that the HD 2900 XT certainly doesn't have in common with the HD 4870 is power needs: the 4800 series, as we saw in our review of the HD 4850 last week, put out a lot of power while maintaining a reasonable power consumption rates. While the HD 2900 XT required both a 8-pin and 6-pin PCIe power connection, the HD 4870 takes two 6-pin's. Diamond recommends only a 450W power supply (or greater) for this HD 4870 -- although, if you have a less expensive 500W or 450W PSU, you might be pushing it somewhat. Still, after shelling out $299 for a video card, it is nice to think that you might get by without having to buy a new PSU, if your still using a 500W PSU.

Specifications

The most notable -- and one of the most impressive -- features of the Diamond HD 4870 is memory performance. The HD 4870 cards are the first ones to run with GDDR5. The vast majority of cards out use GDDR3 -- which has been the standard for sometime now. Even though ATI was first to pioneer using GDDR4, its adoption was fairly limited. But it seems likely that GDDR5 will probably be the de-facto standard for the high-end cards over the next fairly long (in tech terms) stretch of time. This memory is tied to a 256-bit memory interface, which is a bit more limited -- but much cheaper to make -- than the 512-bit and 448-bit memory bus found on NVIDIA's just released GTX 280 and GTX 260. However, as the benchmarks will soon show, seems like 256-bit memory bus offers enough bandwidth to keep the high-speed GDDR5 very happy indeed.

The 4800 series also introduced a number of improvements in AA performance. With the big match-up of the last generation, the HD 3870 versus the 8800 GT, the HD 3870 did lag behind somewhat the 8800 GT when anti-aliasing was used. The Diamond Radeon HD 4870 offers up to 24x custom filter anti-aliasing, and marketing materials suggest that this card will not break hardly a sweat at all at 2x and 4x AA levels.

It seems like in the older days, if you bought a mid-range card, you would play the newest games without AA to reach those higher framerates at first, while perhaps cranking the AA on the older titles in your gaming rotation. Perhaps this is not the case now -- but the benchmarks will help us figure this out.