AMD A8-3870K Unlocked Llano Quad-Core APU Review

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Introduction and Specifications

When AMD initially released their Llano-based A-Series APUs, the company targeted cost-conscious consumers looking for highly-integrated, easy to assemble solutions for an entry-level or mid-range PCs. At the time of launch, the flagship model in the A-Series line-up was the A8-3850, which featured quad CPU cores paired to a DirectX-11 Radeon GPU with 400 active shader units. In our coverage of the A8-3850, we found it to offer decent performance for its price, especially in graphics-related workloads where the APU’s relatively powerful integrated GPU was able to stretch its legs. 

AMD Llano Die Shot...

The original A-Series APU line-up didn’t feature any enthusiast-targeted products, but AMD quickly reacted to the A-Series’ mostly favorable reception with a new flagship, dubbed the A8-3870K Black Edition, which we’ll be showing you here today. In its default configuration, the A8-3870K is a slight upgrade from the A8-3850, thanks to a small increase in its default CPU frequency. The “K” in its part number, however, means the chip is unlocked, which makes for some interesting overclocking. When paired to the right motherboard, which features an updated BIOS / UEFI that fully supports the A8-3870K, this APU is able to hang with some of AMD’s fastest quad-core desktop processors, while also offering discrete-class GPU performance. 

AMD A8-3870K Unlocked "Llano" APU
Specifications & Features
Tech / Package 32nm / FM1 905-pin lidded μPGA, 40x40 mm, 1.27 mm pitch
TDP Configurations 100W configurations
Processor Core “Stars” 32nm HKMG process core (up to 4 cores), 128 KB L1 Cache(64 KB Instruction, 64 KB Data) 1 MB L2/Core, 128-bit FPUs, Unlocked @ 3.0GHz
Memory Up to DDR3 1866
Graphics Core Up to 400 Radeon Cores, DirectX 11 capable, UVD3
Displays Digital Display I/F DP0: Display Port, HDMI, DVI
Digital Display I/F DP1: Display Port, HDMI, DVI
Graphics Features AMD Dual Graphics
Blu-ray 3D
AMD Steady Video
AMD Perfect Picture
DisplayPort 1.1a, HDMI 1.4a
Power Management Multiple low-power states
32-nm process for decreased power consumption
PCIe core power gating
PCIe speed power policy
GPU power gating of Radeon Cores and video decode (UVD3)
AMD Turbo Core technology on select models
Tech/Package 65nm / FC BGA, 605-Ball, 23x23mm, .8mm pitch
TDP Configurations A75: 7.8W, A55: 7.6W
UMI x4 Gen 2
SATA A75: 6 ports at 6 Gb/s, A55: 6 ports at 3 Gb/s
RAID 0,1,10
USB A75: 4 USB 3.0 Ports, 10 USB 2.0 Ports, 2 USB 1.1 Internal Ports A55: 14 USB 2.0 Ports, 2 USB 1.1 Internal Ports
PCIe GPPs 4x1 Gen2
FIS Support A75 only
CIR CIR Receiver
Clock Gen Integrated
Power Rails SVID for VDDCR_CPU & VDDR_NB, fixed voltage for other rails

Software Drivers: Windows 7, Windows Vista, Windows XP, Linux

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The AMD A8-3870K differentiates itself from the A8-3850 it supplants at the top of AMD's A8 APU line-up in two meaningful ways. First, the A8-3870K has a 100MHz higher default CPU clock, 3GHz (3870K) versus 2.9GHz (3850). Second, as the "K" denotes, the A8-3870K is an unlocked "Black Edition" APU. That means the chip is unlocked for more flexible overclocking. It's not only the CPU multipliers that are unlocked though, but the GPU and memory speed multipliers too. The initial batch of "non-K" Llano APUs were all locked, so overclocking was only possible via base clock manipulation. With the A8 K SKUs, however, overclocking of the CPU, GPU, and Memory blocks is also possible via multiplier adjustment.

Just to paint the complete picture, as we've already mentioned, the AMD A8-3870K APU has a default CPU clock speed of 3.0GHz. Its four x86 cores are each outfitted with 128KB of L1 Cache (64KB Instruction, 64KB Data) and 1MB of L2 cache per core, but no L3 cache is present. Phenom II processors have similar L1 configurations, but only half the L2, plus a large 6MB L3 cache. However, remember, this is an APU, so the A8-3870K also has an integrated DX11-class Radeon HD 6550D GPU core. The GPU runs at a default frequency of 600MHz and has 400 active shader ALUs arranged in an array of 5 SIMDs.

Due to the fact that the A8-3870K's CPU cores are only clocked 100MHz higher than the A8-3850 and the main attraction of this APU is its status as an unclocked Black Edition chip, we did some overclocking right out of the gate using a standard air-cooler to see what kind of CPU and GPU performance gains could be achieved with a bit of tweaking. Ultimately, the A8-3870K ended up being fairly overclockable and attained a CPU frequency of 3.5GHz simultaneously with an 800MHz GPU frequency. These are increases of 500MHz and 200MHz, respectively, over their default clocks. Since those numbers were possible with a basic air-cooler and only a minor .25v bump in voltage, we've included a full set of benchmark scores while the A8-3870K was overclocked on the pages ahead.

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