AMD A8-3850 Review: Llano Rocks Entry-Level Desktops

Earlier this month we previewed AMD's Llano architecture in a notebook environment. Now we have the desktop version with a 100 W TDP. How much additional performance can the company procure with a loftier thermal ceiling and higher clocks?

A8-3850 Makes Its Desktop Debut

Don Woligroski did an absolutely killer job on our first look at AMD’s Llano architecture. If you haven’t yet read that story and you want to know more about the plumbing inside the company’s first mainstream APU, you really owe it to yourself to check out The AMD A8-3500M APU Review: Llano Is Unleashed before diving into this piece.

Because Don covered the underlying architecture so well, I’m going to use our first experiences with AMD’s Llano-based desktop platform, code-named Lynx, to dive deeper into the stuff I know you guys love: benchmark results and analysis. What kind of performance can you expect out of Dual Graphics? How does Sandy Bridge with discrete graphics compare? What effect does memory performance have on gaming frame rates? How does integrated USB 3.0 support measure up to some of the add-on controllers we’ve seen? I’ll answer all of that.

But first let’s go over the basics of AMD’s first desktop-class Llano-based APUs.

Llano: The Recession-Friendly APU

Oh, Audi would be so proud (or maybe not, given the entry-level pedigree of these processors). AMD is using the same A8 and A6 designators to distinguish between the perceived performance levels of its four launch SKUs.

There are two A8s and two A6s. The Llano-based flagship is A8-3850, a 100 W part with Radeon HD 6550D graphics, four execution cores with 1 MB L2 cache each, and a 2.9 GHz clock rate. That part does not offer Turbo Core support—the only way to get it running faster than 2.9 GHz is through overclocking.

The A6-3650 is also rated at 100 W, even though it’s armed with Radeon HD 6530D graphics and a more conservative 2.6 GHz clock rate (again, Turbo Core isn’t available). The -3650 boasts four cores as well, includes the same 4 MB of L2 cache, and support DDR3-1866 data rates, just like the other three models. 

Interestingly, dipping down to the 65 W level doesn’t seem to sacrifice much in the way of functionality. AMD’s A8-3800 includes the capable Radeon HD 6550D engine, quad-core Stars architecture, and 4 MB L2 repository. However, Turbo Core helps compensate for a fairly severe drop to 2.4 GHz, kicking frequency up to 2.7 GHz in situations where thermal headroom allows for it. Unfortunately, AMD didn’t send over any Turbo Core-equipped processors for testing, so it’s impossible to gauge how much time this four-core part spends at its elevated setting.

Finally, the A6-3600 is also a 65 W component. It scales way back, though, giving up not only processor clock rate—its four cores running at 2.1 GHz by default and up to 2.4 GHz with Turbo Core—but also graphics performance via the less-complex Radeon HD 6530D engine. Is still includes 4 MB of L2 cache though, complementing each core with 1 MB. UK pricing is said to start at £70 for the A6-3600 to £105 for the A8-3850

What's the difference, exactly, between the Radeon HD 6550D and Radeon HD 6530D GPU engines? One SIMD engine, for the most part.

When you look at a block diagram of the Llano's GPU component, it's easy to see how AMD differentiates these two lineups. Each SIMD hosts 80 ALUs and is associated with four texture units. Turning one SIMD off yields the 320 shaders and 16 texture units offered by Radeon HD 6530D.

A Small Launch Gets Smaller

With four SKUs in the initial Llano-based desktop portfolio, a zero-hour revelation that the 65 W A8-3800 and A6-3600 won't be available until an undisclosed date narrows the family down to two models: A8-3850 and A6-3650, both 100 W parts. As a result, it won't be possible to test Turbo Core functionality on Llano until AMD addresses the availability of its lower-power offerings.