Dedicated accelerators and more
Kaveri is about more than Steamroller and GCN. The dedicated media accelerators on the chip have all been updated, too.
The big addition here is the TrueAudio DSP block that AMD built into the latest Radeons—and apparently into the next-gen game console SoCs, as well. TrueAudio is meant to accelerate effects like 3D positional audio in games, removing that burden from the CPU. Like the HSA features, Kaveri's TrueAudio block is a bit forward-looking, since we don't yet have any software that can take advantage of it. However, a number of middleware vendors look to be gearing up to support TrueAudio, so we can probably expect to see games use it before too long.
Kaveri's video accelerators are both updated versions of the ones featured in Trinity and Richland. The UVD 4 video decoder block hasn't changed much, but AMD says it has improved error resiliency, so videos will continue playing even when the decoder encounters errors in their source files. The VCE 2 encoder block adds support for the YUV444 color format, specifically in order to provide better text quality when using 60GHz wireless displays. H.265/HEVC isn't supported in VCE 2. AMD is instead talking about using GPU acceleration via OpenCL to assist with the playback of 4K video content encoded in this fashion.
Oh, and one big-ticket checkbox item has been marked: at last, AMD's latest APU supports PCI Express 3.0 connectivity for off-chip I/O. This addition could pay dividends in several cases, especially when the APU is paired with a couple of discrete graphics cards in a multi-GPU team.
Like AMD's past APUs, Kaveri has sophisticated power management capabilities, with dynamic voltage and frequency scaling (DVFS) as well as boost. I suspect AMD isn't talking as much about this particular area because it's saving something for the introduction of the mobile Kaveri parts. Compared to prior generations, the firm says, Kaveri has better monitoring of temperatures and activity counters across the chip, allowing it to pursue higher clock frequencies with boost—and thus push the limits of its prescribed thermal envelope—without reducing chip reliability.
AMD did share some preliminary battery life numbers for the mobile version of Kaveri. The numbers above come from a 35W APU installed in a system with a 58Whr battery, and as you can see, the run times look pretty decent—although that is a pretty beefy battery.
One other bit of good news for mobile versions of Kaveri: AMD says the chip draws only about 25 mW of power in an S3 suspend state. That should mean that it's possible to let a laptop sleep for hours or even days without substantially draining the battery. We'll have to see how that works out at a platform and system level, but the APU power number sounds very nice.
A new socket: FM2+
Kaveri comes to the desktop with a new type of socket in tow: Socket FM2+. This new plug type has two more pins than the older FM2 standard, and as a result, Kaveri-based APUs won't drop into pre-FM2+ motherboards.
Happily, Socket FM2+ mobos will accept older Trinity and Richland-based APUs, so there is a measure of backward compatibility in play here. I think most owners of Socket FM2 systems would probably prefer things the other way around, though, so they could drop a new CPU into an older system as an upgrade.
A trio of desktop Kaveris
|A10-7850K||2/4||3.7 GHz||4.0 GHz||4 MB||8||720 MHz||95 W||$173|
|A10-7700K||2/4||3.4 GHz||3.8 GHz||4 MB||6||720 MHz||95 W||$152|
|A8-7600||2/4||3.3 GHz||3.8 GHz||4 MB||6||720 MHz||65 W||$119|
|A8-7600||2/4||3.1 GHz||3.3 GHz||4 MB||6||720 MHz||45 W||$119|
Yes, I said there is a trio of desktop Kaveri APUs. Look closely above, and you'll see that the A8-7600 occupies two lines in the table. That's because this particular model comes with a configurable TDP. The user can pick one of two operating points for it, a 45W peak or a 65W peak, and the chip will run at different clock speeds based on that setting. I've already mentioned that most of Kaveri's improvements will be more acutely felt in lower power envelopes, so perhaps you won't be surprised to learn that AMD has elected to supply the A8-7600 to us for review. I can't really complain. We've long said AMD's 65W APUs are its most attractive offerings.
I do wish the A8-7600 were actually becoming available for purchase today, but AMD quotes a vague "Q1 '14" release time frame for it. The two A10 parts are the ones hitting stores today.
Naturally, we've tested the A8-7600 at both 45W and 65W TDP levels. As a fairly direct competitor to the A8-7600, we've have Intel's Core i3-4330. This dual-core, quad-threaded Haswell runs at 3.5GHz, actually a higher clock than the A8's. That fact doesn't bode well for the CPU performance match-up, since Intel's recent cores tend to be substantially faster clock-for-clock than AMD's. (Then again, Kaveri has twice as many integer cores.) The i3-4330 lists for $138 and has a TDP rating of 54W, smack-dab between the A8-7600's two configurable levels. The Core i3 features Intel's HD Graphics 4600 IGP. Haswell's beefier GT3 and GT3e graphics configs aren't available in socketed desktop parts.
As expected, the A10-series Kaveris can't quite reach the same clock frequencies as Richland parts fabbed on a 32-nm SOI process. The 7850K tops out at 3.7GHz base and 4.0GHz boost speeds, several hundred megahertz below the 4.1/4.4GHz operation of the A10-6800K. Graphics clock speeds are down a bit, too, from 844MHz in the 6800K to 720MHz in the 7850K. Kaveri's wider graphics should still be a clean win, though, provided that there's enough memory bandwidth available in the socket.
To that end, AMD has expanded support for DDR3-2133 memory speeds across the entire Kaveri desktop lineup. In the Richland lineup, the A10-6800K is the only part with official support for DDR3-2133. The others top out at DDR3-1866.
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