HIS Radeon HD 6870 IceQ X Turbo X
Like the Radeon HD 6850, the Barts XT GPU has been fabricated using the 40nm process and features 454 million less transistors than the Radeon HD 5870's Cypress XT core. The Radeon HD 6870 also has the same 255mm2 die size as the 6850.
The core is clocked at an impressive 900MHz, 50MHz higher than the Radeon HD 5870, while the GDDR5 memory operates slightly slower at 1050MHz. Pairing that frequency with a 256-bit memory bus gives the Radeon HD 6870 134.4GB/s of bandwidth, a tad less than the HD 5870.
However, all those X's in the card's branding means this is no standard Radeon HD 6870. The 6870 IceQ X Turbo X features a core clock frequency of 975MHz and a GDDR5 memory speed of 1150MHz (4.6GHz DDR). The former has been increased by 8% and the latter by 10%, which we expect to provide a ~8% performance boost versus a stock clocked board.
The Radeon HD 6870 IceQ X Turbo X's memory operates at 1150MHz using Elpida W1032BABG-50-F modules, which are rated for 1250MHz (5.0GHz DDR). As we mentioned on the last page, this should give us some room to play with.
The Radeon HD 6870 differs from the older HD 5870 in its core configuration, having been downgraded from 1600 SPUs (Stream Processing Units) and 80 TAUs (Texture Address Units) to 1120 SPUs and 56 TAUs, while there are still 32 ROPs.
The AMD reference cooler found on the Barts XT GPU is quite large in its own right, but HIS has replaced it with their IceQ X cooler. The reference cooler is comprised of 30 fins measuring 4.3" (11cm) long, 2.5" (6.5cm) wide, 1" (2.5cm) tall and is connected to the base via three 6mm heatpipes. It's cooled using a 75mm fan that can get quite noisy.
HIS claims that their IceQ X heatsink and fan combo keeps the 6870 IceQ X Turbo 15 degrees Celsius cooler than the reference heatsink. Again, the IceQ X features four large 8mm heatpipes that extract heat from the copper base plate and distributes it across an area of 7.2" (18cm) by 3.2" (8cm) featuring 44 aluminum fins. Those fins are cooled by a large 3.6" (9.2cm) fan that runs incredibly quiet.
As we found when taking a closer look at the HIS Radeon HD 6850, the IceQ X cooler doesn't cover the memory IC's and power circuitry. The same thin aluminum strip cools four power MOSFETs while the memory is passively cooled by an aluminum heatspreader.
To ensure the graphics card gets enough power, the AMD reference design calls for a pair of 6-pin PCI Express power connectors -- identical to what you'd find on the Radeon HD 5870 as well as the GeForce GTX 560 Ti.
The Radeon HD 6870 supports Crossfire technology with a connector to bridge another 6750 and we intend to test this feature. Like the 6850, the 6870's I/O panel has dual DL-DVI connectors along with a single HDMI 1.4a port and two mini-DisplayPort 1.2 sockets. All HD 6870 graphics cards can support a maximum resolution of 2560x1600 on up to three monitors.
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