Sapphire Toxic HD 4870 512MB Review

We’re huge fans of ATI’s Radeon 4800 series GPUs. Both the Radeon 4850 and 4870 rewrote the rules when it comes to performance at their respective price segments, forcing NVIDIA to slash prices on their entire GeForce graphics lineup -- the GTX 260 and GTX 280 saw their prices reduced by hundreds of dollars thanks to the introduction of the 4870 and 4870 X2 GPUs.

The Radeon 4850 and 4870 were also the first mainstream GPUs to deliver viable frame rates when gaming with 8xAA.

The one key weakness of the Radeon 4800s are their stock coolers. The heatsink/fan units ATI developed for both the Radeon 4850 and Radeon 4870 are more focused on keeping noise at bay than actually keeping the GPU cool. GPU temps in the 60 degree Celsius range are typical for 4800 GPUs while idling at the Windows desktop, while load temps can hover in the 80-degree range during gaming.

In comparison NVIDIA’s GeForce 9800 GTX and GTX 260 GPUs typically peak in the mid-to-high 60s at load.


Fortunately the 4800 GPU is designed to operate at these high temperatures. The GPU doesn’t throttle or overheat, even after extended gaming sessions where the GPU is exposed to high temps for a prolonged period of time. However many end users are uncomfortable with their GPU operating at such high temps, after all excessive heat can affect overall system stability and can eventually prematurely kill system components. Besides dust, the #1 cause of most fan failures is excessive exposure to heat.

To tackle this problem ATI’s board partners have developed newer Radeon 4850 and 4870 coolers that are more effective at combating heat while generating very little to no noise.

Sapphire’s Toxic HD 4870 was one of the first Radeon 4870 cards designed to address this problem. The card was also one of the first 4870 boards to hit the market with factory OC’ed clocks.

Improving on the ATI cooling

At the heart of Sapphire’s Toxic HD 4870 512MB is its cooler. Rather than rely on a traditional heatsink/fan unit, Sapphire employs a custom cooling design that consists of their vapor chamber cooling technology (VCT) along with three copper heat pipes and one massive fan. First let’s discuss the vapor chamber cooling.

Sitting directly atop the RV770 GPU is the VCT, which is made from copper and acts much like a traditional heatpipe. The VCT is a sealed vacuum chamber composed of three “wicks”. There’s a vaporization wick, condensation wick, and a transportation wick. Heat from the GPU heats up the water within the vaporization wick, causing it to vaporize. This water vapor then moves through the vacuum until it hits the condensation wick. Here the water vapor condenses and forms back into a liquid (releasing the heat in the process); this liquid is then absorbed by the transportation wick (by capillary action), where it’s then transported back to the vaporization wick and the process is repeated.

But Sapphire doesn’t stop there. Cooling the VCT is a massive dual-slot heatsink along with three long copper heatpipes. Heat from the VCT is absorbed by the heatpipes, while the aluminum heatsink works to disperse heat off the heat pipes (the heatsink also cools the board’s memory modules).

Keeping everything cool is a 90mm fan. By using such a large fan (many case fans are smaller than this), Sapphire doesn’t have to crank up the RPMs in order to move a lot of air. This helps to keep noise levels down. Air from the fan is then exhausted outside the PC case.

We saw drastically reduced GPU temps thanks to Sapphire’s unique cooling solution. The cooler’s fan also generates very little noise during use. Full cooling results can be found on the Overclocking page of this review.

Supercharged clocks and the rest of the card

To improve performance, Sapphire also OCs their Toxic 4870 card. The graphics core clock is bumped up 30MHz over stock to 780MHz, while the board’s 512MB of GDDR5 is clocked at 1.0GHz even. In comparison the Radeon 4870’s memory runs at 900MHz in stock form.

The rest of the card is based on ATI’s reference design. Sapphire makes no modifications to the board layout. Sapphire does include a nice bundle with their card though. Inside the box you’ll find a copy of 3DMark Vantage as well as the game Ruby Rom, PowerDVD, CyberLink DVD Suite, driver CD, two power adapters, an HDMI adapter, DVI adapter, CrossFire connector, and component/composite video cables.