ATI HD Radeon 5870: The Fastest Videocard Ever (PS It's $380)

AMD packs 2.15 billion transistors into a tiny chip, offering outstanding performance, DirectX 11 support, and triple-monitor (or better) capability. Nvidia’s response is nowhere to be seen

AMD’s graphics division, the former ATI Technologies, loves a good surprise. The company has been a perennial also-ran in the graphics performance arena, but every now and then, it one-ups the competition in a big way. That happened back in 2002, with the launch of the original Radeon 9700, which stole the performance lead from archrival Nvidia. It happened again last year, with the Radeon HD 4800 series. The 4850, 4870, and 4890 weren’t always faster than the competition, but they were small, efficient chips that forced Nvidia into a price war that was good for users but bad for Nvidia’s bottom line.

Now AMD’s doing it again, putting some serious hurt on the competition with the first GPU to support Microsoft’s upcoming DirectX 11 API. AMD’s also been paying close attention to the emerging market for non-gaming apps accelerated by GPUs, such as video transcoding and digital photography, fully supporting DirectCompute 11 and OpenCL standards for general purpose computing on graphics cards.

This new chip is no shrinking violet in the numbers department. Every number associated with the new Radeon 5800 series is staggering: 2.15 billion transistors, 2.7 trillion floating-point operations a second, more than 20 gigapixels per second throughput, 1,600 shader units. Other numbers impress because of their smallness. One example: The idle power is a scant 27W— lower than many entry level GPUs.

Given the sheer scale and ambition of this GPU, does it deliver in the performance realm? And will it deliver at a price normal humans can afford? Let’s find out.

Digging into the Radeon HD 5870

At its core is a no-compromise GPU more efficient than any in graphics history

Two years ago, AMD’s ATI division decided to bow out of the game of building huge, hot chips that were expensive to make, ceding the high-end glory to Nvidia’s GT200 chip. That’s not to say AMD gave up on performance; it instead adopted the mantra of building the best performance GPU within a certain cost and power envelope. The Radeon HD 5800 series, originally code-named RV870, is the culmination of that approach. Taking advantage of Moore’s Law, ATI’s designers were able to build a GPU with few compromises using a 40nm manufacturing process.

Radeon GPUs Compared

Radeon HD 4890 vs 5870

	Radeon HD 4890	Radeon HD 5870
Die Size	263mm-squared	334mm-squared
Transistor Count	956 million	2.15 billion
CPU Clock	850MHz	850MHz
Memory Clock	975MHz	1200MHz
Memory Quantity (GDDR5)	1GB	1GB
Manufacturing Process	55nm	40nm
Stream Processors	800	1600
Texture Units	40	80
ROPs	16	32
Maximum Board Power (TDP)	160W	188W
Idle Power	90W	27W

Power and Performance

The new GPU is just 334mm2—30 percent larger than the earlier 4870 GPU, but packing more than twice the number of transistors.

At 27W, the idle power is astonishingly low for such a large chip. The key factor was enabling lower memory clocks and voltages during idle, a feat made possible because of significant improvements in the 40nm manufacturing process. The net result is very low power when the board is just rendering your Windows desktop. At the same time, the VRM (voltage regulator module) interface has been improved, preventing overheating while allowing somewhat higher power consumption when performance is actually needed.

So the HD 5870 can draw less power while it’s doing nothing. But we also expect to see better performance, particularly given some of the other specs listed by ATI. The faster memory gives the 5870 overall memory bandwidth of 153GB/s. Feeding that huge pipe is a GPU with twice as much hardware where it matters—stream processors, ROPs, and texture units.

The graphics engine itself sports some new features—particularly the hardware tessellation engine. While past ATI products have offered hardware tessellation, the new engine fully supports Microsoft’s DirectX 11 tessellation API. ATI is fond of pointing out that this is actually its sixth generation tessellation hardware.