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Graphics: Fewer Shaders, Better Efficiency

AMD Trinity On The Desktop: A10, A8, And A6 Get Benchmarked!
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As Don pointed out in his mobile A10-4600M coverage, shifting Trinity to the VLIW4 architecture first found in AMD’s Radeon HD 6900-series cards allows it to deploy fewer shaders, but take better advantage of them. By then turning clock rate up or down (depending on thermal headroom), it’s able to improve performance without adding a lot of complexity to the APU itself.

At its most feature-complete, Trinity’s Devastator graphics processor includes as many as six SIMD engines, each with four texture units and 16 thread processors. There are four ALUs in each thread processor, adding up to 384 total shaders and 24 texture units.

Sliding down AMD’s stack, SIMD engines are gradually turned off and clock rates are dialed down to create differentiation. The A10s both have 384 shaders. The A8s lose two SIMDs (and eight texture units), creating a 256-shader component. AMD’s A6-5400K sports three SIMDs, totaling 192 shaders. And the A4 looks to be a 128-shader offering.

Dual Graphics

Like Llano, Trinity supports Dual Graphics configurations—cooperative rendering using the on-die Radeon engine and a discrete card of roughly comparable potency. Although I don’t have any of the models AMD lists in its support matrix, I did discover that a Radeon HD 6670 does the trick as well.

Our baseline blue bars represent the Radeon HD 7660D built into the A10-5800K APU. The green bars are our Radeon HD 6670 on its own. And the red bar is both graphics engines working cooperatively.

At 1280x720 there isn’t enough graphics load to let Dual Graphics shine before this platform runs into a processor bottleneck. The gap opens up at 1680x1050, though, and continues to show off the benefit of Dual Graphics at 1920x1080, where the integrated Radeon HD 7660D and Radeon HD 6670 average almost 100 FPS.

Discrete GPU
Desktop APU
Discrete Graphics Code-Name
Radeon Product Name
Recommended Memory
A6-Series
HD 7540D
A8-Series
HD 7560D
A10-Series
HD 7660D
Desktop Configurations
Turks XT
HD 7670
GDDR5
Discrete Available
Discrete RecommendedDiscrete Recommended
Turks Pro
HD 7570
GDDR5Discrete AvailableDiscrete RecommendedDiscrete Recommended
Turks Pro
HD 7570
DDR3
Discrete Recommended
Discrete RecommendedDiscrete Recommended
Caicos XT
HD 7470
DDR3Discrete RecommendedDiscrete AvailableDiscrete Available
Caicos Pro
HD 7450
DDR3Discrete AvailableNo Discrete (APU-Only)
No Discrete (APU-Only)
All-in-One Configurations
Onega LP
HD 7670A
GDDR5Discrete RecommendedDiscrete RecommendedDiscrete Recommended
Onega LP
HD 7650A
DDR3Discrete RecommendedDiscrete RecommendedDiscrete Recommended
Caspian XT
HD 7470A
DDR3Discrete RecommendedDiscrete AvailableDiscrete Available
Caspian Pro
HD 7450A
DDR3Discrete AvailableNo Discrete (APU-Only)No Discrete (APU-Only)
Cedar
HD 7350A
DDR3No Discrete (APU-Only)No Discrete (APU-Only)No Discrete (APU-Only)


We also benchmarked Batman: Arkham City using the Low quality setting preset and found that performance actually slid backward with Dual Graphics enabled. The version of the driver we tested, however, still doesn't offer Dual Graphics support in anything but DirectX 11 applications. You don't get DX 11 features in Batman until you choose a higher preset. Fortunately, AMD has a beta driver (Catalyst 12.6) that adds DirectX 9 compatibility, too. We didn't have time to give it a spin before today's piece, but it's something we'll follow-up on.

What we do know from WoW is that Dual Graphics has serious potential on this platform. Notably, the setup process is significantly easier than it was back when I evaluated Llano. You simply plug in the discrete card, keep your display attached to the on-board GPU, and install the drivers. Dual Graphics even gets enabled automatically now.

Display Connectivity

Another advantage that Trinity holds over Llano is Eyefinity support. The new APU includes four display controllers, whereas its predecessor only included two. That means you can do three- or four-way monitor configurations, providing you use the right combination of outputs. Four screens, for example, require DisplayPort 1.2 multi-streaming on at least one output. A trio of screens is easier. You can use two non-DisplayPort panels, plus one DisplayPort- or VGA-equipped screen as the third.

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