Forget AMD Kaveri, Carrizo On The Way

AnandTech | AMD Announces Carrizo and Carrizo-L, Next Gen APUs for H1 2015

While not a surprise that Carrizo is coming, it's nonetheless good to hear that it is indeed on the way. What with the slow/non-existant launch of several Kaveri mobile processors, I think it's very appropriate to forget about Kaveri at this point, and start focusing on Carrizo instead!

For me, the most disappointing news is Carrizo will still be 28 nm, and the voltage adaptive operation is perhaps the most interesting, as if it does cut 10-20% of power use, that could go a long way towards making up for the same process and improving AMD's position power-wise. Of course, it will all be for naught, in terms of getting my money, if there aren't at least a few high-end models launched this time around, so I'm hoping this time the OEMs deliver on that.

(By the way, I propose that the current "Next-gen AMD CPU's" thread be focused on Zen, since that's been its current focus, and this be focused on Carrizo. That way we can more or less keep the discussion focused on one generation in each thread)

 

The voltage adaptation does sound quite interesting. I wonder how that works without impacting performance. On the other hand... still 28nm? Seriously? By H1 2015, the 22nm process will be 3 years old (first Ivies came out in April 2012). Even given the fact that Intel has gotten lazy, at the rate this is going, AMD will be behind by two nodes rather than one.

 

It is coming fast after Kaveri, not even laptops available yet with Kaveri (at least with the fastest one). Sad still no 45W version, which would reduce significantly the throttling issues under gaming. Hopefully this the last APU based on Buldozer cores :hi2:.!

 

They are making these chips in GlobalFoundries. I don't think they are on 22nm yet. If they wanted to move to TSMC it would take a major redesign. Although there are rumors that AMD did make some Kaveri chips at TSMC.

 

The way I understand it is that, since the CPU will downclock if the voltage gets low, they'll be able to run the voltage a fair amount lower. In the infrequent cases where the CPU does have to downclock due to insufficient voltage, it will have a small impact on performance. But I think the theory is that they can lower voltage considerably while still keeping those downclocks infrequent enough (and short enough) that the impact on performance will be negligible, perhaps not noticeable. They did note that the CPU reacts to the voltage within nanoseconds, and if the downclocks are also on the order of nanoseconds - or even hundreds of nanoseconds - they probably wouldn't be noticeable so long as they were infrequent. Of course, we'll see how well it works in practice when Carrizo comes out.

Seems logical to me, though, considering my laptop. Its Core 2 Duo runs at 1.225V or so by default, IIRC. But I can safely undervolt it to 1.025V. I used to be able to get 1.0125, but it seems to be a little less tolerant as it gets older (maybe it just needs repasted?). At any rate, when it was in its prime, 1.0125V was safe, and 1.000V often was, but every so often it would crash - often enough that I wouldn't run it at 1.000. If it had had something like this, it could have downclocked when the 1.000V actually wound up being more like 0.994 or whatever was too low and made it reset, and it could've saved that extra 0.0125V, saving another 2% or so power. And that's 2% after my optimizations - it would've been a lot more significant relative to the factory voltage. So the rationale makes sense to me.

Carrizo, as part of Excavator (Carrizo is to Excavator as Kaveri is to Steamroller), is supposed to be the last revision based on the basic Bulldozer design. Then it's on to Zen, or whatever the next-gen winds up being called. I'm also looking forward to post-Bulldozer-based, but the graphics side has progressed enough lately that Carrizo still has me somewhat interested.