There's a great deal riding on the launch of AMD's next-generation Kaveri
APU. The new chip will be the first CPU to incorporate significant architectural changes to the Bulldozer CPU AMD launched two years ago and the first chip to use a graphics core derived from AMD's GCN
(Graphics Core Next) architecture, which debuted on the desktop two years ago as well. A strong Kaveri launch could give AMD back some momentum in the enthusiast business -- and that's something the company could use.
Now, leaked slides point to a Kaveri APU that's coming in hot -- possibly a little hotter than AMD anticipated.
Kaveri's Steamroller CPU core separates some of the core functions that Bulldozer unified and should substantially improve the chip's front-end execution. Unlike Piledriver, which could only decode four instructions per module per cycle (and topped out at eight instructions for a quad-core APU), Steamroller can decode four instructions per core
or 16 instructions per quad-core module. That's not going to double performance in and of itself, but it should offer a significant uplift.
Unfortunately, AMD's new CPU comes with a significant clock loss. The A10-7850K reportedly has a base clock of 3.7GHz and a maximum Turbo Mode of 4GHz compared to a 4.1GHz base / 4.4GHz Turbo for the A10-6800K
. Cutting the clock speed by 10% may bring the chip into the desired power envelope, but it would also explain why we've heard reports that Kaveri's CPU improvement isn't very good. If Kaveri outperforms Piledriver by, say, 15-20% clock-for-clock, but then drops its clock speed by 10%, most of the gain evaporates.
The A10-7850K will offer a 512 core GPU while the A10-7700K will be a 384-core part. Again, GPU clock speeds have come down, from 844MHz on the A10-6800K to 720MHz on the new A10-7850K. This should be somewhat offset by the gains from moving to GCN from the VLIW4
architecture used in previous parts, but the chip is taking a 15% clock hit. Graphics performance should still be 15-20% better thanks to a vastly wider core. The top-end part should improve performance over Trinity
by 15-20% depending on the game, while the A10-7700K should be modestly faster than the previous hardware. The new GPUs will support Mantle
and AMD's TrueAudio standard.
If the chip overclocks well, the A10-7850K could give AMD a serious improvement over previous parts, though it's not going to close the gap dramatically with Haswell. Current indications are that the A10-7850K is a 95W TDP. That implies there's going to be a little headroom for TDP, but not a huge amount.
One thing we don't know yet is whether Kaveri will support the new Crossfire DMA engine that improves the R9 290X and R9 290's performance in multi-GPU mode. Kaveri could be an ideal dual graphics solution if frame pacing is improved between the asymmetric GPU configuration.