AMD-ATI Radeon HD 2900 XT Performance Preview

Introduction

It’s no small secret that ATI’s highly anticipated DX10 part, codenamed R600, has been under development for quite some time now. It’s also no secret that R600 has suffered from numerous delays.

Much like ATI’s last next-gen introduction, R520, ATI is once again late to the game and playing catch up, only this time the stakes are higher, as this is ATI’s first major graphics launch under the combined AMD-ATI entity: make a mistake here, and it will affect the financials of the new AMD, a company which is already under a considerable amount of financial pressure. Of course, if the R600 launch is successful, AMD’s fortunes could swing in the other direction as the orders for DX10-compliant GPUs pour in from OEMs looking to refresh their mobile and desktop lineups, while enthusiasts pick up cards at the e-tail and retail levels. Needless to say this is a pretty big deal for AMD, and today’s opening salvo, the Radeon HD 2900 XT, has the specs on paper to really impress, but more on this later…

Let’s clear up what’s probably been the number one question we’ve received since the AMD-ATI buyout was announced: branding. Officially the latest Radeons will be branded as the ATI Radeon HD 2000 family of products from AMD. The Radeon HD 2000 line will start with the Radeon HD 2400 series, with prices starting below $99, while AMD’s mainstream solution, the Radeon HD 2600 series, will be priced from $99-$199. The flagship card will be the ATI Radeon HD 2900 XT from AMD, and will be priced at $399.

The Radeon HD 2900 XT should hit retail shelves starting today, while the other cards won’t arrive en masse until the end of June.

For the notebook market, AMD is also announcing new Mobility Radeon parts ranging from the Mobility Radeon HD 2300 for the value/entry-level segment, to the Mobility Radeon HD 2600 for performance notebooks. In between these two GPUs is the Mobility Radeon HD 2400 line, which will service the thin and light sector. According to AMD notebooks built around the Mobility Radeon HD 2300 should begin shipping in the May-June timeframe, but we won’t see laptops built with the other GPUs ship until sometime in July.

AMD-ATI Radeon HD 2900 XT Performance Preview [ @ 1280 x 960 ] > View Full-Size in another window.

We’ll go over all the fine details of these parts later in this article, today we’re going to focus on AMD’s flagship part formerly known as R600, the Radeon HD 2900 XT. The specs for the Radeon HD 2900 XT have been leaked multiple times over the past few months, but we’ll provide them again just in case you missed it:

Unified Superscalar Shader Architecture

320 stream processing units
- Dynamic load balancing and resource allocation for vertex, geometry, and pixel shaders
- Common instruction set and texture unit acces supported for all types of shaders
- Dedicated branch execution units and texture address processors
128-bit floating point precision for all operations
Command processor for reduced CPU overhead
Up to 80 texture fetches per clock cycle
Up to 128 textures per pixel
Fully associative multi-level texture cache design
DXTC and 3Dc+ texture compression
High resolution texture support (up to 8192x8192)
Lossless Z and stencil compression (up to 128:1)
Lossless color compression (up to 8:1)
8 render targets (MRTs) with anti-aliasing support
Physics processing support

Full Support for DirectX 10.0

Shader Model 4.0

Geometry Shaders

Stream output

Integer and bitwise operations

Constant buffers

State objects

Texture arrays

Dynamic Geometry Acceleration

High performance vertex cache

Programmable tessellation unit

Accelerated geometry shader path for geometry amplification

Memory read/write cache for improved stream output performance

Anti-aliasing Features

Multi-sample anti-aliasing (up to 8 samples per pixel)

Up to 24x custom filter anti-aliasing (CFAA) for improved quality

Adaptive super-sampling and multisampling

Temporal anti-aliasing

Gamma correct

Super AA (CrossFire configurations only)

HDR+AA

Texture Filtering Features

2x/4x/8x/16x high quality adaptive anisotropic filtering modes (up to 128 taps per pixel)

128-bit floating point HDR texture filtering

Bicubic filtering

sRGB filtering (gamma/degama)

Percentage Closer Filtering

Depth and stencil texture (DST) format support

Shared exponent HDR (RGBE 9:9:9:5) texture format support
CrossFire Multi-GPU Technology

Scale up rendering performance and image quality with 2 or more GPUs

Integrated compositing engine

High performance dual-channel interconnect

ATI Avivo HD Video and Display Platform

Two independent display controllers
- Drive two displays simultaneously with independent resolutions, refresh rates, color controls, and video overlays for each display
- Full 30-bit display processing
- Programmable piecewise linear gamma correction, color correction, and color space conversion
- Spatial/temporal dithering provides 30-bit color quality on 24-bit and 18-bit displays
- High quality pre- and post-scaling engines, with underscane support for all display outputs
- Content-adaptive de-flicker filtering for interlaced displays
- Fast, glitch-free mode switching
- Hardware cursor
Two integrated dual-link DVI display outputs
- Each supports 12-, 24-, and 3-bit digital displays at all resolutions up to 1920x1200 (single-link DVI) or 2560x1600 (dual-link DVI)
- Each includes a dual-link HDCP encoder with on-chip key storage for high resolution playback of protected content
Two integrated 400MHz 32-bit RAMDACs
- Each supports analog displays connected by VGA at all resolutions up to 2048x1536
HDMI output support
- Supports all display resolutions up to 1920x1080
- Integrated HD audio controller with multi-channel (5.1) AC3 support, enabling a plug-and-play cable-less audio solution
Integrated Xileon HDTV encoder
- Provides high-quality analog TV output (component/S-Video/composite)
- Supports SDTV and HDTV resolutions
- Underscan and overscan compensation
HD Decode Acceleration for H.264/AVC, VC-1, DivX and MPEG-2 video formats
- Flawless DVD, HD-DVD, and Blu-ray playback
- Motion compensation and IDCT (inverse discrete cosine transformation)
HD Video Processing
- Advanced vector adaptive per-pixel de-interlacing
- De-blocking and noise reduction filtering
- Edge enhancement
- Inverse telecine (2:2 and 3:2 pull-down correction
- Bad edit correction
- High fidelity gamma correction, color correction, color space conversion, and scaling
MPEG-2, MPEG-4, DivX, WMV9, VC-1, and H.264/AVC encoding and transcoding
Seamless integration of pixel shaders with video in real time
VGA mode support on all display outputs

512-bit, 8-channel GDDR3/4 Memory Interface

Ring-Bus Memory controller
- Fully distributed design with 1024-bit internal ring bus for memory reads and writes
- Optimized for high performance HDR (high dynamic range) rendering at high display resolutions

700 Million Transistors on 80-nm HS fabrication process
OpenGL 2.0 Support
PCI Express x16 bus interface

Notes

On paper AMD’s Radeon HD 2900 XT certainly looks impressive. It boasts over 320 stream processing units and a 512-bit memory interface, that’s twice as wide as ATI’s previous high-end offering, the Radeon X1950 XTX.

R600’s stream processors are arranged as a 5-way design, with its memory interface consisting of eight 64-bit memory controllers; in comparison the Radeon X1950 XTX relied on eight 32-bit memory controllers for its 256-bit memory interface. The chip is built on a special high-speed derivative of TSMC’s 80-nm manufacturing process (normally 80-nm is reserved for value and mainstream parts) and consists of over 700 million transistors. That’s nearly twice the number of transistors as Radeon X1950 XTX, which incorporated 384 million transistors, and 19 million more transistors than the G80 GPU inside NVIDIA’s GeForce 8800.

Another feature that’s been discussed extensively is audio. Rumors have swirled that R600 boasts an integrated 5.1 audio controller, leading many to believe that R600 would handle audio-processing duties, but we can report that ATI’s audio solution is merely a pass-through solution using the PCI Express interface to connect to your existing audio card. This is useful for home theater PC (HTPC) users who would like to connect their HDTV to their PC over HDMI. Previously you had to run a separate cable from your graphics card to your sound card in order to pass audio to your HDTV via HDMI. With AMD’s latest Radeons, this cable is no longer necessary.

Looking over the specs, you’ll also no doubt see ATI’s new 24x custom filter AA mode.