ATI Mobility Radeon X1600 Preview

The Mobility Radeon X1600 GPU is essentially identical to the desktop Radeon X1600, save for its lower clock speeds and potentially smaller compliment of frame buffer memory. Whereas the desktop Radeon X1600 family of products will have their GPU's clocked at speeds ranging from 500MHz - 590MHz, with 128MB-256MB of memory clocked at 780MHz - 1.38GHz, the Mobility Radeon X1600 as it was configured in the Asus A7G notebook we used for testing had both its core and memory clocked at 470MHz. Clock speeds will likely vary based on the particular notebook design, however.

ATI Mobility Radeon X1600: Architectural Overview The GPU's Main Features

Architectural Overview: Mobility Radeon X1600

Like its desktop counterpart, the Mobility Radeon X1600 is equipped with 12-pixel shader pipelines (three 4-pipe shader cores), 5-vertex shaders, 4 texture units, and 4 render back-end units (ROPs). It also offers all of the features introduced with the Radeon X1K graphics family, including High Dynamic Range rendering with Anti-
Aliasing, Parallax Occlusion Mapping, Volumetric Lighting, Dynamic Soft Shadows, and the AVIVO video engine, among many others. For a much more comprehensive look at the ATI Radeon X1K family of products, we suggest you take a look at our initial coverage from back in October.  We cover the X1K architecture in far more detail in that article.

ATI Mobility Radeon X1600: The Platform The Chips & The Notebook

ATI PowerPlay Control Panel

The Mobility Radeon X1600 will be available as a standalone GPU, or packaged as a multi-chip module with its frame buffer memory included, like the one pictured here. The GPU is manufactured using TSMC's low-K 90nm process with copper interconnects, to allow for higher clock speeds at lower core voltages. In fact, in "low power" mode, the Mobility Radeon X1600 requires less than 1v to operate. It also incorporates all of the mobile specific features that encompass ATI's "PowerPlay" feature set, including Dynamic Lane Count Switching (DLCS) which dynamically changes the PCIe lane count from x16 to x1 when switching from AC to battery power. The Mobility Radeon X1600 also has three user-controlled modes when powered by AC or battery - Performance, Balanced and Battery - as you can see in the screen shot above.  The remaining PowerPlay features that are supported include Dynamic Clock Gating and Power-On-Demand.

A new tweak in the architecture of the Mobility Radeon X1600, that aims to reduce power consumption due to current leakage, is "Back Biasing". Basically, with Back Bias, low voltage and low current is applied to the die in the opposing direction, which helps reduce current leakage from transistors in their 'off' state. According to ATI, Back Bias reduces power consumption resulting from unwanted current leakage by up to 20%.

You can't very well evaluate a mobile GPU without a notebook powered by it, so for our testing we were presented with the first shipping notebook featuring the Mobility Radeon X1600, the Asus A7G. This notebook will initially be offered only in overseas markets, but could eventually find its way to the states under a different name. The A7G's main feature set includes:

We like the A7G's styling, and were impressed by its feel and aesthetic. We were also especially impressed by its 17" "Color Shine" LCD. This particular LCD seemed to be a great match for the Mobility Radeon X1600. It offers a native resolution of 1400x900, which looked great.  But it was the scaling on the LCD that really stood out. When running at non-native resolutions, lower than 1400x900, on-screen images looked very clear and sharp, and lacked the usual level of "blurriness" associated with running LCDs at non-native resolutions. Representatives from ATI claimed that the reason for the excellent scaling was AVIVO and the Mobility Radeon X1600's scaler.