Product: Sapphire Radeon HD 6670
Company: AMD
Authour: James Prior
Editor: Charles Oliver
Date: April 19th, 2011
Core Architecture

AMD Radeon
AMD Radeon
The Turks core architecture receives the same improvements that Barts and Caicos did over their predecessors (Cypress and Cedar); namely, improved graphics engine, new tessellation unit and updated render processors for improved anisotropic filtering (AF) quality. The GPU core is made using TSMC's 40nm process, like the previous Evergreen powered HD 5000 lineup. If some of this information seems familiar, we first looked over the 6500 and 6600 series specifications when they appeared as OEM only cards.


Turks Architecture
Turks Architecture

The Universal Video Decoder (UVD) hardware is updated to version 3, from Redwood's v2.2. This significant addition improves the card's hardware accelerated video capabilities, including support for Blu-ray 3D offload and DiVX acceleration. The HD 6000 series is certified for Blu-ray 3D playback, and uses the UVD 3 to offload decoding from the CPU. Audio capabilities are unchanged from the HD 5000 series, offering multi-channel bit-streaming LPCM support including Dolby TrueHD and Dolby DTS Master Audio for Blu-ray protected audio playback. These audio options are handled by an on-card Realtek HD Audio processor, which can output either via the DisplayPort 1.2 output or HDMI 1.4a connector (but not both simultaneously).

UVD 3
UVD 3

Compared to Redwood, Turks offers up some significant changes. The number of transistors is up (Turks rocks 716M compared to Redwoods 627M) but some key numbers are down - power being the good one.

HD 6670 Engineering Sample
HD 6670 Engineering Sample

Turks XT, used in the HD 6670, features an 800MHz engine clock which is a 25MHz bump over Redwood XT / HD 5670. An extra 80 stream cores have been added, bringing the total to 480 and 6 SIMDs (4+1 stream cores per thread processor; 16 thread processors per SIMD). This brings another 4 texture units to the GPU, increasing the texture and pixel fillrate of the HD 6670 over the HD 5670. This bigger, faster GPU is claimed to be ~25% faster than Redwood XT, if we're counting single precision - 768GFLOPS for the new vs. 620GFLOPS for the old. The memory configuration appears unchanged, still specifying 1GHz GDDR5 via a 64-bit memory interface, although our HD 6790 sample only features four memory chips total vs. the 5670's eight. As a coup de grace for the 6670 vs 5670 spec fight, Turks XT also manages to drop 2W idle power and 4W load, while likely mostly due to the reduced memory chip count is also due to the core's architecture improvements.

HD 6570 Engineering Sample
HD 6570 Engineering Sample

Turks Pro, the HD 6570, follows the tradition of Redwood Pro in that Turks Pro is different from the XT version only by clocks and memory options. The engine clock of the Turks Pro card is specified at 650MHz, and features all 5 SIMDs in 480 stream processors. Texture units, render back end count, all remain the same with the 64-bit memory interface. Turks Pro cards can be specified with 1GB of 900MHz DDR3 or 512MB of 1GHz GDDR5. Initially, the HD 5500 series was not available equipped with GDDR5, but was added after a couple of months by many AIB partners. Using DDR3 significantly drops the specified load power of the HD 6570, knocking 16W off, at the expense of available memory bandwidth. Turks Pro boasts 724GFLOPS to Redwood Pro's 520GFLOPS.

The engineering sample boards AMD supplied look extremely similar to the HD 5500 series samples we received in February last year, and in fact the new Turks GPUs use the same package as Redwood. This benefits AMD and their partners as less design work is required to create PCBs, as the existing design can be tweaked to include whatever new power and output requirements the new chips need. Like the HD 5570 and HD 5670, the Turks cards are positioned to be media experience cards with decent compute capabilities and capable of gaming at 1680x1050 or 1920x1080 resolutions, depending on which card you pick.

Sapphire Radeon HD 6670
Sapphire Radeon HD 6670

Add in board partners have some flexibility in their design and specification of their cards, so retail samples may differ in appearance, as our Sapphire HD 6670 does. Both the 6670 and 6570 are Eyefinity capable, with AMD specifying that the 6670 will be 4-display capable. This will depend on partner output choice, as while our engineering samples feature DVI, VGA and DisplayPort outputs, Sapphire smartly decided to trade the VGA output for HDMI 1.4a output. Both DVI and DisplayPort can be adapted to HDMI, but for simplicity native connections work best. However, VGA connections can be ribbon connected for half-height/full height conversion. Sapphire's HD 6670 features two phases vs. our engineering samples which are equipped with one on their half-height PCB designs.

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