Barely six months after debuting on the desktop, AMD's RV770 graphics processor is going mobile. AMD has announced a whole range of Mobility Radeon HD 4000 GPUs for notebooks, and the highest-end parts have surprisingly tantalizing specs.
The Mobility Radeon HD 4800 series is derived from the same RV770 silicon that powers the desktop Radeon HD 4870, and it looks pretty similar on paper: 800 stream processors, support for both GDDR5 and GDDR3 memory types, a 256-bit memory interface, and CrossFire capability. Obviously, though, AMD has made some tweaks and reduced clock speeds to keep power consumption in check. The company says it'll be up to notebook makers to set exact clocks, but it expects the fastest Mobility Radeon HD 4800 graphics modules to slip into power envelopes smaller than 75W.
In much the same vein, the Mobility Radeon HD 4600 series is based on the same silicon as desktop Radeon HD 4600 offerings: both have GPUs with 514 million transistors, 320 SPs, and 128-bit memory interfaces. AMD told us the 4500 and 4300 Mobility offerings have GPUs similar to their desktop brethren, too.
|SPs||Transistors||Computing power||Memory interface||Memory types||Memory bandwidth|
|Mobility Radeon HD 4800||800||956 million||880 GFLOPS||256-bit||GDDR3, GDDR5||89.6GB/s|
|Mobility Radeon HD 4600||320||514 million||432 GFLOPS||128-bit||DDR2, DDR3, GDDR3||25.6GB/s|
|Mobility Radeon HD 4500 and 4300||80||242 million||108 GFLOPS||64-bit||DDR2, DDR3, GDDR3||12.8GB/s|
These similarities are especially noteworthy in light of Nvidia's fastest mobile GPU—the GeForce 9800M GTX—which has a lot in common with the $130 GeForce 9800 GT.
Speaking of the GeForce 9M line, AMD's new Mobility Radeons have an equivalent feature that lets users switch back and forth between discrete and integrated GPUs without rebooting. AMD says the switch can be either manually triggered or automatic (occurring when the system is plugged into AC power), and according to this page, this feature works with Intel chipsets.
AMD didn't tell us which notebook makers will introduce Radeon HD 4000-based laptops, but the company snagged design wins from HP, Dell, Lenovo, Gateway, Asus, and many others with its Mobility Radeon HD 3000 series. In fact, Asus announced new N81Vp and N51Tp laptops with Mobility Radeon HD 4600 GPUs just yesterday. AMD expects the bulk of Mobility Radeon HD 4000-based notebooks to start shipping in the March-April time frame.