AMD Launches Mobile Kaveri APUs

AMD Mobile Kaveri SKUs

The previous generation Trinity/Richland APUs came in four variants: at the top were the highest performance 35W TDP standard voltage (SV) parts, and then we dropped into the ultra-low voltage (ULV) range with several variations: 25W, 19W, and 17W TDPs were all available. With Kaveri, AMD is mostly consolidating their lineup into two classes: SV 35W TDP parts, and ULV 19W TDP parts. AMD did mention at one point that the 19W parts can be configured to target different TDPs, however, allowing the laptop OEM to target anywhere from 15W to 25W if desired. There's also at least one 17W TDP part, which we'll get to in a moment.

One other item that AMD emphasized was their new idea of "Compute Cores", which is a way for them to compare performance potential of CPU and GPU cores. GPUs typically have hundreds of cores that are good for very specific tasks whereas CPUs have a few cores that are general purpose, but the GPU functionality is becoming increasingly complex so AMD wanted a way to compare them. For the purposes of Kaveri (and GCN graphics cards), AMD has defined a Compute Core as being "any core capable of running at least one process in its own context and virtual memory space, independently from other cores." What that means is each GCN Compute Unit counts as a Compute Core, and each CPU thread (two per Steamroller module) counts as a Compute Core.

Starting at the top with the 35W APUs, these will be the highest performance mobile parts. At launch there will be three 35W APUs: the "entry" A8-7200P, "mainstream" A10-7400P, and "enthusiast" FX-7600P. All three APUs use the P suffix to indicate that they’re 35W parts. And right away, we see some interesting changes from the Trinity/Richland lineup.

First, you're sure to notice the use of the FX branding. Make no mistake: this is the same APU as the other Kaveri parts and it has no relation to the desktop FX processors; AMD marketing simply feels the FX brand has a good reputation among enthusiasts and consumers and they wanted to carry that over into the mobile world. Of course this also solves the question of what to call the new highest-end APU; Llano had A4/A6/A8 while Trinity used A6/A8/A10; Kaveri will use A6/A8/A10/FX (so no A12 for now; sorry).

Looking at the core clocks, the base clocks haven't changed too much (2.4-2.7GHz with Kaveri compared to 2.1-2.5GHz on Richland), but Turbo Core clocks have gone up quite a bit. AMD noted that a lot of work went into tuning the mobile Kaveri APUs for power, with one of only four Corporate Fellows at AMD being in charge of that area. The result is that Kaveri should run closer to its Turbo clock in many situations, and the maximum clock speeds have increased from 3.0-3.5GHz on Trinity/Richland to 3.3-3.6GHz on Kaveri. That might not seem like a big deal at first, but keep in mind a couple of points. First, at the same clock speed the Steamroller cores in Kaveri should be about 15-20% faster than the Piledriver cores in Trinity/Richland, thanks to architectural improvements. Second, on the desktop Richland actually topped out at 4.1/4.4GHz while Kaveri only reaches 3.7/4.0GHz, so while Kaveri still enjoys architectural improvements it had to be clocked slower; we don’t see that with the mobile parts.

AMD's Joe Macri (Corp VP and Product CTO Global Business Unit) discussed some of the design decisions that went into Kaveri, noting that choosing the right type of transistor for an APU is different than building a pure CPU. At a high level, there are “V” shaped transistors frequently used with CPUs that can run at higher clock speeds, and “T” shaped transistors that tend to work better in the highly parallel design of GPU cores. From what I could gather, AMD used "V" transistors in Trinity/Richland but has switched to "T" transistors for Kaveri, which explains the drop in maximum clock speed. Joe also noted that 47% of the Kaveri core is dedicated to GPU, again highlighting the importance of the transistor choice.

Moving over to the GPU side of things, each of the 35W APUs comes with a different GPU configuration, using 256, 384, or 512 stream processors for the A8/A10/FX parts, respectively. GPU clock speeds top out at 686MHz with Kaveri compared to 720MHz with Richland, so this is another small step back but GCN’s architectural efficiency and increase in SPUs in the FX-7600P should more than compensate. That said, feeding these increasingly powerful GPUs becomes an increasingly difficult task, which is why maximum memory clock speeds are up to 1866MHz for the A8 and A10, and meanwhile the FX processor goes one further to 2133MHz. Given just how hard it is to feed a fully enabled APU like the FX-7600P – a problem we’ve already seen on the similarly configured desktop SKUs – the memory bandwidth increase is a welcome sight.

Moving on to the 17W/19W parts, there's apparently a single 17W APU, the A6-7000, along with three 19W APUs. (AMD didn't provide details on the A6-7000 at the briefing, but we've since confirmed the above specifications, and there's also a Pro equivalent -- see below.) Richland had two 17W parts and one 19W part, so AMD has sort of flipped roles here. As expected the 17W A6-7000 is a rather lean chip; it has one Steamroller module and 192 GCN steaming processors (for a total of five Compute Cores, if you're counting), with a base/turbo CPU clock speed of 2.2GHz/3.0GHz while the GPU turbo clock stands at 553MHz. Compared to the previous generation Richland processors, the A6-7000 gains all of Kaveri’s architectural improvements along with an additional 200MHz for the maximum CPU turbo clock. GPU clock speeds on the other hand take a hit, but this is offset by GCN’s greater performance and a badly needed increase in the maximum DDR3 memory clock speed. In fact with mobile Kaveri, DDR3-1600 is now the baseline, with all processors supporting 1600 or better.

Meanwhile the 19W parts all have two Steamroller modules, and maximum base/turbo clock speeds only differ by 300MHz; most of the differentiation comes in the GPU department. The A8-7100 includes four GCN CUs, the A10-7300 has six CUs with slightly higher GPU clocks, and the FX-7500 also has six CUs with another moderate bump in clock speed. AMD has also brought along the "R-series" branding for the GPUs, so the A6-7000 gets an R4 GPU, the A8 is an R5, A10 gets an R6, and the FX has an R7 GPU. Maximum GPU clocks are again down in some cases compared with Richland, though architectural difference should more than cover any loss in clock speed.

There's one final category of APUs, which appear to be AMD's equivalent of Intel's SIPP (Stable Image Platform Program) CPUs: the AMD Pro Series. There are three Pro APUs, the A10 Pro-7350B, A8 Pro-7150B, and A6 Pro-7050B. These APUs are functionally equivalent to the FX-7500, A10-7300, and A6-7000 respectively. The Pro series targets business customers with a message of commercial stability and management. AMD guarantees that these APUs will remain available for an extended period of time, so enterprise customers won't need to worry about validating new hardware for a couple years.

Besides offering different levels of performance, AMD is also differentiating their Kaveri APUs based on other features. Eyefinity and TrueAudio support will be limited to the A10 and FX APUs; the A6/A8 APUs lose this functionality. Similarly, the A6 does not have Dual Graphics functionality; I didn't have much luck with Dual Graphics on Richland/Trinity laptops, but with the iGPU and dGPU both being GCN architectures now there's at least more potential to extract additional performance through CrossFire. Finally, note that the A6 APUs get ARM TrustZone functionality, whereas the higher-end A8, A10, and FX APUs do not.

All of the above was discussed previously (and then pulled), but we have something new to add with today's launch: a performance preview.