Feature Articles

AMD Radeon HD 6790 - Confusing and Unnecessary

By Kenny Yeo - 21 Apr 2011

Confusing Nomenclature

Confusing Nomenclature

AMD’s Radeon HD 6000 series (Northern Islands) has come under threat recently thanks to NVIDIA’s recent releases. Thanks to the better optimized GF110 chip, NVIDIA has quite successfully rejuvenated their Fermi series of cards. The hot and extremely power hungry cards such as the GeForce GTX 480 and GTX 470 are now days of the past. And today, the awesome GeForce GTX 580 leads the way with recent releases such as the GeForce GTX 560 Ti and GTX 550 Ti have combining great performance, efficiency and affordability.

The aforementioned GeForce GTX 550 Ti was NVIDIA’s latest part, and was meant to replace the older GeForce GTS 450. Changes at the transistor level and improved clock speeds have greatly increased the performance of the GeForce GTX 550 Ti over the older GTS 450, but the new part still trails the GeForce GTX 460 and GeForce GTX 560 Ti greatly.

With NVIDIA still scrambling for something to plug the gap, AMD has seized the chance to release their own new card. Aimed at the mainstream segment and set to go head to head against the GeForce GTX 550 Ti, AMD has introduced the Radeon HD 6790. Confusingly, despite being introduced as the first card in the Radeon HD 6700 series, the HD 6790 is actually powered by a variant of the Barts GPU used in both the Radeon HD 6870 and HD 6850.

The latest card from AMD is the Radeon HD 6790 and it effectively uses a scaled-down version of the Barts chip that powers the earlier Radeon HD 6870 and HD 6850.

Specifically, the Radeon HD 6790 uses a variant of the Barts GPU and is codenamed Barts LE. It has 800 stream processing units, which is 160 lesser than the Radeon HD 6850 and 320 down compared to the Radeon HD 6870. And compared to its closest relative, the Radeon HD 6850, the Radeon HD 6790 will have 8 less texture mapping units at 40, but the same number of raster operating units at 32. Also, like the cards in the Radeon HD 6800 series, the Radeon HD 6790 will have 1GB of GDDR5 framebuffer running on a 256-bits wide memory bus interface. Clock speeds, however, have been boosted to 840MHz at the core and 4200MHz DDR at the memory, which are higher than the Radeon HD 6850’s equivalent 775MHz and 4000MHz DDR.

Finally and curiously, the Radeon HD 6790 will have a higher rated TDP of 150W, as compared to the HD 6850’s 127W. This is unusual considering the Radeon HD 6790 is positioned as a less powerful product, but we will reveal in our power consumption tests later in the article to see if the Radeon HD 6790 will indeed consume more power under real world testing conditions.

In many ways then, judging from past releases, the Radeon HD 6790 should really have been the Radeon HD 6830. AMD’s decision to name it the Radeon HD 6790 is beyond us, but it wouldn’t be an understatement to say that the current nomenclature of the Radeon series is pretty darn confusing, even for us.

Anyhow, here’s how the card stacks up against competitive SKUs.

AMD Radeon HD 6790 and competitive SKUs compared
Model AMD Radeon HD 6790 AMD Radeon HD 6850 ATI Radeon HD 5770 NVIDIA GeForce 
GTX 550 Ti
NVIDIA GeForce GTS 450 NVIDIA GeForce GTX 460
Core Code Barts LE Barts PRO Juniper XT GF116 GF106 GF104
Transistor Count 1700 million 1700 million 1040 million 1170 million 1170 million 1950 million
Manufacturing Process 40nm 40nm 40nm 40nm 40nm 40nm
Core Clock 840MHz 775MHz 850MHz 900MHz 783MHz 675MHz
Stream Processors 800 Stream Processing Units 960 Stream Processing Units 800 Stream Processing Units 192 Stream Processors 192 Stream Processors 336 Stream Processors
Stream Processor Clock 840MHz 775MHz 850MHz 1800MHz 1566MHz 1350MHz
Texture Mapping Units (TMU) or Texture Filtering (TF) units 40 48 40 32 32 56
Raster Operator units (ROP) 32 32 16 24 16 24
Memory Clock 4200MHz DDR 4000MHz DDR 4800MHz DDR 4100MHz GDDR5 3608MHz GDDR5 3600MHz GDDR5
DDR Memory Bus 256-bit 256-bit 128-bit 192-bit 128-bit 192 / 256-bit
Memory Bandwidth 134.4GB/s 128GB/s 76.8GB/s 98.5GB/s 57.7GB/s 86.4 / 115.2GB/s
PCI Express Interface PCIe ver 2.0 x16 PCIe ver 2.0 x16 PCIe ver 2.0 x16 PCIe ver 2.0 x16 PCIe ver 2.0 x16 PCIe ver 2.0 x16
Molex Power Connectors 2 x 6-pin 1 x 6-pin 1 x 6-pin 1 x 6-pin 1 x 6-pin 2 x 6-pin
Multi GPU Technology CrossFireX CrossFireX CrossFireX SLI SLI SLI
DVI Output Support  1 x Single-Link, 1 x Dual-Link 1 x Single-Link, 1 x Dual-Link 2 x Dual-Link 2 x Dual-Link 2 x Dual-Link 2 x Dual-Link
HDMI  1 1 1 1 (mini-HDMI) 1 (mini-HDMI) 1 (mini-HDMI)
DisplayPort Yes (DisplayPort 1.2)  Yes (DisplayPort 1.2) 1 None None None
HDCP Output Support  Yes Yes Yes  Yes Yes Yes
Street Price  Launch price: US$150 ~US$174 ~US$129 ~US$159 ~US$129 ~US$199


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