APU Design

There are quite a few changes here in the APU line-up, including the use of AMD's new x86 architecture featuring “Piledriver” cores. These cores have a few features of their own compared to previously released Bulldozer cores found on current AMD FX desktop chips. I've listed the new features below:

• Supports up to 4 cores and has support for the latest ISA instructions, including FMA4/3, AVX, AES, and XOP
• Branch Prediction and Cache enhancements over the previous “Bulldozer” cores
• 2MB L2 cache per dual-core module (up to a total of 4MB)
• Max Turbo Frequencies up to 4.2GHz
• Configurable via AMD OverDrive

It's interesting to see that Turbo frequencies of the Piledriver CPU cores match that of previously released Bulldozer FX CPUs, with some additional new features to boot. Overall, the design hasn't changed much from what AMD has previously offered with desktop CPUs, but it is definitely quite different from what was offered in previous FM1 APUs. The offered amounts of cache are the same, but we see dual 2MB groupings, one for each Piledriver module. There are up to two modules in each APU, making for a total of "up to 4 cores".


The GPU portion of AMD's APUs has seen a slight update as well, and again, the details are listed below.

• Featuring VLIW 4 architecture
• Up to 384 shaders
• Up to 800MHz
• Up to 8xAA and 16AF support
• DirectX 11 Support
• Controllable via AMD OverDrive

The GPU side of the APU has undergone much more drastic changes by adopting the VLIW 4 shader design. Previous Llano chips saw 400 shader cores and a VLIW 5 shader design, while these new chips just see 384 shader cores. This change is very similar to going from a 5-series AMD Desktop GPU to a 6-series AMD Desktop GPU. Also new is the ability to clock the GPU via AMD OverDrive, a feature that was sorely missing from previous FM1 parts.


With all of those changes, the pin layout for these new AMD FM2 APUs has changed slightly as well, as illustrated in the picture above. That picture has the new FM2 APU on the left and the older FM1 APU on the right. There's actually one less pin in use with the new APUs. One of the other places that had a pair of missing pins on the older FM1 APUs has been moved over slightly as well. As I mentioned earlier, AMD had to update the AM3 socket to get full support for Bulldozer-based FX chips. AMD named their upgraded variant AM3+ and explained that their design change was necessary due to changes in power delivery. It only makes sense that the same changes were needed when introducing Piledriver to the APU design, since the older APUs had a different CPU core design that resembled older Socket AM3 CPU cores. It's interesting to note that PCIe 3.0 has not been adopted here, and I am not sure when AMD will be offering PCIe 3.0 with their CPU products, but it does seems a bit out of place not to have PCIe 3.0 because the socket is changing anyways.