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AMD Radeon HD 6800 series cards (AMD Barts)

Meet the new series of graphic cards — specification and architecture analysis


As a result of “Barts” graphic core optimization, AMD managed to achieve performance level of 2 TeraFLOPS together with significant decrease of dies size.

AMD Barts architecture

GDDR5 memory is paired up with 256-bit width memory interface.

AMD Barts micro-architecture

The architecture of AMD “Barts” (picture above) is very similar to what previous generation cards — AMD “Cypress” (picture below) — have:

Cypress micro-architecture

Let us compare details of both GPUs in the table below:

Release dateSeptember 2009October 2010
Process technology40 nm40 nm
Transistor count2.15 billion1.7 billion
Die size334 mm2255 mm2
Stream Processor16001120
Texture Units8056
Z/Stencil ROPs128128
Memory bus256-bit256-bit

There were some major “cut-downs” in AMD “Barts” architecture. Except for one thing: the AMD “Barts” now has two dispatch processors followed by a doubled amount of instruction cache. As a result, with considerable reduction in performance configuration, new GPU is only slightly less powerful than AMD “Cypress”. This is the case when quantity turns into quality:

Specification comparison of Radeon HD 6870 and HD 5850

We have already seen similar architecture optimization in NVIDIA GF104 graphic processor (GeForce GTX 460 graphic cards).

AMD Radeon HD 6870has a full-fledged processor, therefore, the number of execution block has now been changed. AMD Radeon HD 6850 has two SIMDs locked which resulted in reduced number of Stream Processor — 960.

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