AMD A8 3870K review - Turbo core and North bridge

Turbo Core

A feature that you guys know from AMD's Hexacore processors is of course AMD Turbo Core. Llano now has AMD Turbo Core embedded and that means that the processor can throttle the clock frequency of the CPU cores independently above the base clock frequency for a short period of time.

The APU constantly measures factors like threaded workload, power limitations, voltages and heat levels for both the CPU and GPU. Based on algorithms, the clock frequency of the CPU cores will change. If you are using Photoshop and apply a filter, then for a short burst the Turbo Core mode will kick in and accelerate the CPU cores' clock frequency a little higher. Would you use the GPU in Photoshop (creates more load/heat) then that Turbo mode forfeits and makes sure the processor cores remain at their reference clock frequency.

Turbo Core however is not present in all APUs, ironically the A8 3870 as tested today has its clock frequencies fully opened without any Turbo functionality.

Northbridge

We explained that the Llano architecture has a lot more inside of it than just the CPU and GPU, there's core logic for the UVD engine but also high-level Northbridge functionality including a PCI-Express 2.0 controller and a dual-channel DDR3 memory controller.

That memory controller is again based on the Phenom/Athlon II architecture but optimized to support higher frequency memory. This was needed to give the GPU harbored inside the A8 APU as much memory bandwidth as possible. 

So, straight out of the box higher memory DDR3 frequencies are supported. The Llano dual-channel memory controller as such supports DDR3 memory up-to 1866 MHz, and that's quite a gain from the previous 1066/1333 MHz support. Hey, for graphics the generic rule is simple; the faster the frame buffer memory the better.

Integrated into Llano's Northbridge is also a PCI-Express 2.0 controller that comes with 24 available lanes. You can use 16 for a dedicated graphics card.

Four PCI-Express lanes will be used connecting to the A75 FCH chipset, the data that has to be sent back and fourth between the Llano APU and the FCH (SouthBridge Fusion Controller Hub) uses a so-called UMI link which is basically a fourth PCI Express x4 interface that provides 2GB/s worth of bandwidth in each direction. The residual four links can be used for extra controllers like audio, Ethernet or USB 3.0.