Review: Single-slot, yet very quiet
The Atomic branding on the Radeon HD 3870 card just sounds high-end, and we eagerly awaited for it to show us that Sapphire still has what it takes. Sapphire took RV670's GPU and had a green light to play with GPU and memory clocks, and of course, to develop a new cooling system. The reference design is usually good enough to keep the card temperatures at bay, but we and every other enthusiast out there always want better and more efficient cooling.
For the new technology to develop it takes time and a lot of effort, if you want to have something good and revolutionary. Sapphire has taken a shorter route and took Vapor Chamber technology and effectively implemented it to cool down the graphics card, branding it Vapor-X GPU cooling.
The cooler was named Atomic, and the same brand was just passed on to the card, Sapphire Radeon HD 3870 Atomic Edition.
The Vapor-X cooler works similar to heatpipe technology, but it is much more advanced, and it uses clean water and a process called water vaporization. In the process of cooling water gets vaporized by heating, and vapor fills the vacuum chamber. The vacuum chamber has low air pressure, which enables water to evaporate much faster. An important role is played by three layers in the vapor chamber, a vaporization wick, a condensation wick and a transportation wick. The GPU and memory are in direct contact with the vacuum chamber and they represent the heat source that heats the vaporization wick. The created vapor then moves freely in all directions toward the colder part of the chamber where it comes in contact with cold parts of cooler air and becomes plain water again. The condensation wick then takes that water and the transportation wick routes it back to the vaporization wick.
The good side of this type of cooling is that the vacuum chamber is only 3mm thick, so it is possible to create efficient single slot cooling, which is better than the reference dual slot heatpipe based cooler. The vacuum chamber covers almost the entire cooler. The only drawback is that the hot air remains inside the case, but that is the price you have to pay when you use a single slot cooling solution.
The front side of the cooler reveals aluminum fins, which are cooled by a small fan and which are in direct contact with the vacuum chamber. The fan is quiet, and the entire cooler is much more effective than the reference one.
Sapphire Atomic HD 3870 is based on the RV670 GPU, which is works at 775MHz for reference cards. It was expected for Sapphire to overclock this card, and they decided that 825MHz is the magical number. This is a boost of just 50MHz, but it is as far as it goes with single slot cooling. We managed to push it all the way to 860MHz, which is a better result, but the card was completely stable only at 845MHz.
The memory is also overclocked and it works at 1200MHz for 512MB of GDDR4, which is not that bad when compared to reference 1125MHz. The card uses Samsung K4U52324QE-BC08 memory chips, which are rated to work at 1200MHz (0.8ns) just as Sapphire decided to clock them. We overclocked the memory all the way to 1300MHz, but we didn't want to push our luck with additional overclocking.
If you intend to use Crossfire with four cards, then Sapphire Atomic is the card for you, since it can only be done with single slot cards, at least for now.
Even if the single slot card gives you enough room to go for the quad Crossfire they still leave the hot air inside the case, while dual slot blows it out of the case, at least in ATI's reference design cooler. That is the only drawback of this single slot cooling solution, so if you decide to plug a few of these cards together, you might want to keep an eye on the case temperature.
Sapphire's Atomic HD 3870 isn't great when you take a look at the card's clocks, but bundle certainly is, so it earned a page for itself.