Board analysis

The most obvious difference between ATI’s Radeon 4890 reference design and Sapphire’s Toxic HD4890 is the Toxic board’s cooler. Both cards utilize heatpipe cooling, but Sapphire takes it to another level with their Toxic cooler.

At the heart of the Sapphire cooler is their vapor chamber cooling technology. We’ve written about this numerous times in the past, so we won’t rehash the detailed explanation of how the tech works here, but to make a long story short, vapor chamber cooling acts much like a heat pipe only it boasts lower thermal resistance than heat pipes, with higher heat conductivity as well. From the consumer’s point of view, Sapphire flattens their vapor chamber cooler into an ultra-thin chamber about the size of a conventional thermal plate. In fact, if you don’t look closely for the vapor chamber, you could easily confuse Sapphire’s cooling for a conventional heat plate.

Sapphire’s vapor chamber cooler is made completely from copper, which improves its ability to draw heat off the GPU thanks to copper’s superior thermal conductivity.


Sapphire doesn’t stop there though. To help the vapor chamber do its job Sapphire also adds three heat pipes to further aid in GPU cooling. The heat pipes are rather long, you can literally see them poking out of the right side of the cooler, and are made from aluminum. If you recall, ATI’s Radeon 4890 reference cooler features three heat pipes as well, but they aren’t this large (although they are copper).

Cooling the heat pipes is a dual-slot aluminum heatsink. This heatsink is outfitted with dozens of long fins, which helps to increase the surface area of the heatsink. Finally, at the base of the heatsink is a large thermal plate. Its primary responsibility is cooling the board’s memory modules, although it also helps to dissipate heat off the PCB.

An additional heatsink is also used to cool the board’s power circuitry. This is also found on the 4890 reference design, but the heatsink Sapphire employs has much larger fins than the stock ATI cooler (the heatsink on the ATI reference design is restricted in height due to the card’s blower-style fan).

Sapphire finishes the GPU cooling off with a fan that’s nearly 90mm in size: that’s bigger than many case fans! By using such a large fan, Sapphire can keep everything cool without having to crank up the fan’s RPMs to unbearably high noise levels. At idle, the fan ran in the 1640-1690 RPM range, and peaked to just 1850 RPMs while running looped Crysis timedemo runs. This allowed the Toxic card to run whisper quiet in operation.


Besides the beefed up cooling, the other hardware change Sapphire employs over the stock Radeon 4890 reference design is the use of an 8-pin power connector. Out back you’ll see that Sapphire employs one 6-pin PCIe power connector, and one 8-pin power connector. The 8-pin connector is capable of supplying the GPU with up to twice the power of a 6-pin connector, 150W versus 75W, so by integrating an 8-pin power connector instead of the second 6-pin connector, Sapphire is seriously upping the amount of juice that the card draws. In theory, this should improve your odds when OC’ing.

The 8-pin power connector is required in order for the board to operate; slapping a 6-pin PCIe connector in there isn’t enough. Thankfully Sapphire does include an 8-pin PCIe-to-Molex adapter.

In our testing with the card underclocked to run at Radeon 4890 speeds, the Toxic board consumed 21W more juice under load than the Radeon 4890 reference board under the same conditions: 314W for the Toxic vs the 4890’s 293W (idle consumption was within 1W).

The rest of the board’s design is the same as the stock Radeon 4890 reference board. Sapphire makes no changes to the board-level components, although they do utilize their trademark blue PCB rather than the red PCB ATI uses on their reference design.

Toxic clocks

Sapphire ups the clock speeds pretty significantly with their Toxic 4890. The graphics core is OC’ed 110MHz to 960MHz, an improvement of 11%. The board’s memory is also OC’ed, although not quite as dramatically, running at 1050MHz. This is 75MHz higher than the Radeon 4890’s 975MHz memory and equates to a 7% performance boost.

The other neat feature about the Sapphire Toxic 4890 card is that the card’s BIOS grants you higher maximums in Overdrive. Whereas the bone stock Radeon 4890 is limited to a maximum OC of 1.0GHz in Overdrive, with the Sapphire Toxic board installed you can crank the Overdrive slider up to 1.1GHz.

The memory slider can be dialed up an extra 100MHz too: while the stock Radeon 4890 is capped at 1200MHz memory, you can run the Toxic card’s memory up to 1300MHz.

Accessories

Sapphire ships the Toxic HD 4890 with a healthy bundle of software and accessories. Included inside the card’s packaging is a fresh copy of 3DMark Vantage, PowerDVD 7 (6-channel edition), and CyberLink’s DVD Suite, which includes a range of different CyberLink programs.

Hardware accessories include the aforementioned 8-pin power connector, a 6-pin PCIe power connector, CrossFire cable, DVI and HDMI adapters, a component video cable, and composite video out.