Sapphire - Radeon HD6870 FleX Edition review


The first card to feature Sapphire's FleX solution for AMD's Eyefinity technology, the Radeon HD5770 FleX, went down a storm when it was launched in mid-2010. It enabled users to create a three-monitor Eyefinity setus without having to buy a monitor with the specialised DisplayPort input, or use an expensive dongle. Now that technology has been added to AMD's new Radeon HD6000 series GPUs, in the form of the Radeon HD6870 FleX Edition.

Under the hood

The HD6870 FleX is build around a standard HD6870, one of the 'Bart' cores, using a Sapphire-designed PCB and cooler to keep everything nice and stable.

The clock speeds for the core and memory are as those of the reference design: 900MHz for the core and the 1120 Stream processors; 1,050MHz (4.2GHz effective) for the 1GB of GDDR5 memory that runs via a 256-bit bus. The memory chips are rated at 1,250MHz (5GHz effective), so there's some headroom for a bit of overclocking, should you feel the need.

Keeping this lot cool is one of Sapphire's own-designed heatsink and cooler combinations, which uses three 8mm heatpipes to transfer the heat from the GPU to the aluminium fins of the heatsink. These in turn are cooled by the centrally located 11-bladed fan.

Eye Eye

Usually, if you want to build a three-monitor Eyefinity setup, you have to use both DVI ports, and then the extra DisplayPort as the feed for the third monitor. This involves either buying a special DP-enabled monitor (not exactly thick on the ground), or using a third-party dongle.

Sapphire's engineers have been busy beavering away at the output technology used by EyeFinity, and by using an Analogix chip on the board, they've got rid of the need to use a DP monitor or dongle on the FleX Edition boards.

Instead, they card uses used the HDMI port to provide the output for the third monitor. If you don't happen to have a monitor that supports HDMI - no problem, Sapphire bundles a HDMI-to-DVI adaptor with the card.

If you do happen to have DP monitor or dongle lying around then, that would enable you to hook up a fourth monitor. In all, the HD6780 FleX will support up to five displays.

Framing by numbers

We intended to give the HD6870 FleX Edition a good workout by using three 24in monitors, which would have given a resolution of 5760x1200 to test. Unfortunately, one of the monitors decided it didn't want to play so were we left using two panels, with a total resolution of 3840x1200 for the FleX Edition to cope with. And it did so admirably.

Tested with FarCry 2, using the built-in benchmark as small ranch map (all in game details set to Ultra and no extra filtering) at 1920x1200, the card produced a frame rate of 85.23fps, which dropped to a still-playable 48.40fps at 3840x1200 with 4xFSAA and 4xAscF added for good measure. It was pretty much the same story with Just Cause 2 (Dark Tower map): 59.89fps at 1920x1200, and 35.38 fps at 3840x1200.


Bundled with the card are all the cables and hardware to get you going: an HDMI cable, passive Flex cable (HDMI-to-DVI convertor), mini-DisplayPort-to-standard-DisplayPort convertor, VGA-DVI adaptor and a CrossFire bridge.

Sapphire - Radeon HD6870 FleX Edition features - Verdict

The original HD5770 FleX was good. The latest card to carry the FleX name is even better, thanks to the updated architecture of the HD6870. It performs well, you can set up a three-screen Eyefinity system without a DisplayPort monitor anywhere in sight - and oh... it's very, very quiet.


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