Last month saw the launch of the 6870, a card that messed up the naming scheme somewhat and made the high-end nomenclature a little confused. No longer the fastest single-gpu card, the 6870 launched aside another name-changer: the 6850. While it is an unintuitive comparison (similar to comparing an apple with an orangutan), the 6850 does not replace the current 5850 – instead, it’s more like a 5830 v2.0.
Running at the heart of the 6850 is the same ‘Barts’ core that was used in the faster 6870 model, though in this case it’s reduced in core speed from 900MHz to a more sedate 775MHz. The memory bus is thankfully left untouched and accesses the 1GB of GDDR5 memory chips through a 256-bit bus, which provides bucketloads of bandwidth; especially when taking the shader unit count into consideration. The 6850 lags behind the 6870 by 160 shader units; though transistor counts remain the same at 1.7 billion, demand for memory access is invariably less.
On the flipside is a benefit to losing out on shaders: the power consumption at load drops to 127 watts, saving a cool 24 watts when running at full tilt. It’s not quite low enough to be handled within a single-slot cooler, but it’s definitely manageable. AMD seem to be taking a hands-off approach, and rather than enforcing a reference design like has been done in the past, partners have the ability and freedom to create their cards whichever way they please. Cue a raft of crazy designs!
Sapphire has chosen to cool the card with a simple dual-slot heatsink that places a large fan slightly off-centre, but directly over where the processing core lies. This fan is exceptionally quiet at idle, barely registering on our sound-level meter at only 46.1dBA, and only generating 54.7dBA at load – most cards are this loud at idle! Cool air is sucked in by the fan and passed through an aluminium-finned heatsink contained entirely within the glossy plastic shell of the card, where the cool air becomes warm air and moves along the inside of the shell to be exhausted at both ends. Heat is drawn from a copper plate that contacts the processing core by heatpipes, which are quite literally pipes that heat can move through, which dump their heat into the aluminium fins. Unfortunately the design of Sapphire’s cooler means that most heat will wind up inside the case and won’t be vented outside, so as always, we recommend that you have a high-airflow case to keep components stable.
It definitely seems more than capable of cooling the 6850’s low-fat heat load, and an idle temperature of 36 degrees was so cool that heat could barely be noticed when touching the card itself. Though a load of 64 degrees did produce noticeable warmth, it’s not an excessive amount, and is certainly lower than the 6970 et al.
Performance of the 6850 is actually quite tempting compared to the 5850: returning ten per cent fewer frames in Crysis; 18 per cent slower in Lost Planet 2; identical performance in Unigine Heaven tessellated (though it was 13 per cent slower without tessellation); and was shy of the 5850 by P849 in 3DMark Vantage, a gap of six per cent.
For a price $60 lower than the 5850, the 6850 is 25 per cent cheaper while only dropping behind slightly in performance. Compared to the 5830, the 6850 is a clear winner. While there is a lot that it’s not – a high-end card, a powerhouse performer, a heavyweight champion, or a great overclocker – the 6850 is very tempting value for those after gaming below the price barrier.