Product: AMD Radeon HD 6790
Company: AMD
Authour: James Prior
Editor: Charles Oliver
Date: April 6th, 2011
AMD Radeon HD 6790 Launch Review

Radeon
Radeon
When AMD launched the Radeon HD 6000 series of Graphics processors (codenamed Northern Islands) they were quite clear and up front about the status of the then current generation. The AMD Radeon HD 5800 series was replaced with two product lines, the HD 6800 Barts GPUs and the HD 6900 Cayman GPUs. The AMD Radeon HD 5700 series, codenamed Juniper was going to continue in the market, with only one change - price.


AMD Radeon Product Stack
AMD Radeon Product Stack

This was all well and good, until late January when details of an AMD Radeon HD 6700 series leaked - using that same Juniper core, without any apparent changes. AMD created the HD 6700 series to provide a new BIOS for running Blu-ray 3D in hardware, validated for use by OEMs - you can't buy the HD 6750 or 6770 Juniper cards unless you buy a PC equipped with one. Blu-ray 3D support was one of the new features highlighted in Northern Islands UVD 3.0 hardware, missing from Juniper and instead reproduced in software via the STREAM cores. By limiting this product to OEM only, and clearly describing it as using the same technology as inside the 5700 series, AMD hoped to avoid the negative connotations associated with rebranding last generation cards into this generation with only feature checkbox changes.

This left the HD 5770 fighting in the consumer space (and in select Apple products) against some stiff competition - the GeForce GTS 450, GTX 460 (SE and 768 variants) and recently launched GeForce GTS 550 Ti. Obviously, some of these competition cards also compete against the HD 6850, but the $50-60 price difference between the 5770 and the 6850 leaves NVIDIA some breathing room in a very competitive market space; arguably the most competitive.

AMD Radeon HD 6790
AMD Radeon HD 6790

In early 2010, AMD had this same problem with the HD 5770 and the HD 5850 - a large price and performance gap, with an NVIDIA product sitting nicely in the middle in both price and performance metrics. AMD's answer at the time was the AMD Radeon HD 5830 - the card used the bottom binned Cypress LE core GPU, but with select features disabled - half the ROPs disabled, less SIMDs and texture units. Once settled into the $200 price point, it offered a nice price/performance ratio but was criticized for its power characteristics - due to the bottom-binned nature of the ASICs used, it required a little more juice than the more powerful HD 5850, confusing some who thought that while the 30/50/70 final two-digit suffixes of the 5800 series relative performance, it should also indicate relative power consumption, too.

AMD Radeon HD 6790 Specifications

  • $149USD SEP

  • 40nm AMD Barts LE core

  • 840MHz engine clock

  • 800 STREAM cores (VLIW-5)

  • 10SIMD

  • 1GB GDDR5 VRAM

  • 1050MHz (4.2Gbps QDR) Memory Clock

  • 256-bit Memory Interface

  • 40 Texture Units

  • 16 ROPs

  • 20W Idle / 151W Load

  • AMD 2-way CrossFireX Support

  • 5 outputs: DL-DVI + SL-DVI + HDMI 1.4a + 2 mini-DisplayPort

This time around, the answer to the question is the AMD Radeon HD 6790. This new product doesn't feature a Juniper core, like its OEM-only 6700 siblings, but instead uses the Barts LE core. Once again, the performance is tuned using the lowest binned ASICs (read: possibly worst transistor current leakage) and disabling select features to get the product sitting at the right place. Unlike last time, AMD has the advantage of waiting for NVIDIA's 550 Ti to see where the Barts LE powered HD 6790 should be positioned.

AMD VISION
AMD VISION
So why call it the 6790? AMD tells us its due to the reduced render back end (RBE) configuration and performance increase over the HD 6770 OEM (i.e. HD 5770), being about 20%, by their measurements. With the same number of stream cores (800), and the same number of ROPs (16) as Juniper based cards, Barts LE is a better fit in the empty HD 6700 stack than tacked on the bottom of the HD 6800 series. Today we're looking at the performance of the 6970 in HD resolution and Eyefinity 3 configuration - against the AMD ATI Radeon HD 5830, AMD Radeon HD 6850 and EVGA GeForce GTX 460 SC.


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