Friday, April 24th 2020

AMD Ryzen 3 3300X Isn't Just a Speed-Bump of the 3100: CCX Gymnastics at Play

AMD has announced its Ryzen 3 "Matisse" quad-core desktop processors, with two SKUs in the pipe, the $99 Ryzen 3 3100 and the $120 Ryzen 3 3300X. Both are 4-core/8-thread parts spaced apart by clock-speeds, or so we thought. According to an alleged AMD presentation slide leaked to the web, the differentiation between the two runs deeper than that. Both chips are based on the "Matisse" multi-chip module, with a single 8-core "Zen 2" chiplet that has four disabled cores. How AMD goes about disabling these cores appears to be the secret sauce behind the "X" on the 3300X.

Inside each "Zen 2" chiplet, the 8 cores are spread between two 4-core CCX (compute complexes). On the 3100, AMD disabled two cores per CCX, and halved the 16 MB L3 cache per CCX. So it ends up with a 2+2 core CCX configuration, 8+8 MB of L3 cache adding up to 16 MB. The 3300X takes the more scenic route. An entire CCX is disabled, all four cores are part of the same CCX. This design lowers inter-core latency among the cores, and more importantly. gives each of the four cores access to 16 MB of shared L3 cache. And then there's the speed-bump. This goes a long way in explaining how the 3300X is shown within striking distance of the Core i7-7700K in leaked Cinebench scores, and could provide a formidable gaming processor in the lower end.
AMD Ryzen 3 3100 3300X CCD Configuration
Source: HardwareLuxx.de
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19 Comments on AMD Ryzen 3 3300X Isn't Just a Speed-Bump of the 3100: CCX Gymnastics at Play

#1
Punkenjoy
The fact that the 1 CCX version with 16 MB cache (3300x) Perform so well without having to handle the Inter-CCX communication mean that Zen 3 8 Core CPU (1 chiplet design) are probably going to perform really well.

I suspect that AMD will keep 1 chiplet Zen 3 cpu to lower clock speed and boost frequency to make sure it do not harm too much the 2 chiplets SKU.
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#2
dj-electric
F for that media dude who just had to take a screenshot of one of the slides.
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#3
Cranky5150
I think we will see alot of low priced gaming boxes with the 3300x in them. That is a pretty fast little chip TBH..
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#4
londiste
Cranky5150
I think we will see alot of low priced gaming boxes with the 3300x in them. That is a pretty fast little chip TBH..
I think there is a reason AMD did not come out with Ryzen 3s sooner and your 'little chip' comment illustrates the very likely reason. These CPUs are not little. This is the exact same CPU layout that all Ryzen 3000 CPUs up to 3800X have. Yes, harvesting semi-functional CCDs but these CPUs are neither small nor cheap.
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#5
Lightofhonor
londiste
I think there is a reason AMD did not come out with Ryzen 3s sooner and your 'little chip' comment illustrates the very likely reason. These CPUs are not little. This is the exact same CPU layout that all Ryzen 3000 CPUs up to 3800X have. Yes, harvesting semi-functional CCDs but these CPUs are neither small nor cheap.
Yeah, for the 3100 at least they are saving parts that are partially non-functional to increase yields. For the 3300X they are basically taking parts that would normally be 3800X.
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#6
Punkenjoy
AMD processors strategy is probably all about binning. Theses cpu have probably been collected over time like the latest EPYC CPU that have a lot of disabled cores. They get released laters because they wait to have a a significant piles of cpus that can be used for this without loosing too much money.

By example
- 3950x CPU got released later when they had enough 8 core chiplet that go high in frequency
- Latest Epyc CPU are made from chiplet that have low count of working core but working cache.
- Theses cpu are made to collect the chiplet that have more than 2+ core not working per chiplet.

AMD goal is to maximise profits while reducing as much loss. I doubt they will try to sell willingly a chiplets that could go in a EPYC/Ryzen 7 or 9 in theses CPUs. They are probably everything that they couldn't sell otherwise in their lineup and they are just empying the stock.
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#7
londiste
Lightofhonor
Yeah, for the 3100 at least they are saving parts that are partially non-functional to increase yields. For the 3300X they are basically taking parts that would normally be 3800X.
Not really. There are 8 cores on a CCD, the dies used for 3100 and 3300X differ in which cores are broken. 3700X/3800X use a fully functional CCD.
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#8
Lightofhonor
londiste
Not really. There are 8 cores on a CCD, the dies used for 3100 and 3300X differ in which cores are broken. 3700X/3800X use a fully functional CCD.
Ah, you are right. I have a 3700, but was still thinking 2700X 8-core max. So in both cases it's non-function, just less so on the 3300x.
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#9
Chrispy_
londiste
Not really. There are 8 cores on a CCD, the dies used for 3100 and 3300X differ in which cores are broken. 3700X/3800X use a fully functional CCD.
It'll be interesting to see if anyone does a clock-matched comparison of these two, since it'll give us the performance penalty for crossing Zen 2's CCD interconnects.
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#10
Tomgang
Smart move from AMD. They have a cpu layout to re use properly to broken Chiplets suitable for 3600 or better with to many broken cores and by using this layout. They can re use more broken Chiplets by different quad-core layouts.

So they get cpu models that can compete with intels lowest tier 10000 series, re using broken Chiplets = more profit to amd and less waste to be thrown out. Good for the environment. This just shows how beneficial Chiplet design really is. You can get a to tier cpu like 3950X and also a cheap quad-core out of same design and re use more Chiplets than a all in one chip design like Intel properly can re use.
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#11
Apocalypsee
Interesting, I imagine AMD will do this ever since Ryzen 1st gen but they did it now. Would love to see in-depth review once this gets out.
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#12
AnarchoPrimitiv
Punkenjoy
The fact that the 1 CCX version with 16 MB cache (3300x) Perform so well without having to handle the Inter-CCX communication mean that Zen 3 8 Core CPU (1 chiplet design) are probably going to perform really well.

I suspect that AMD will keep 1 chiplet Zen 3 cpu to lower clock speed and boost frequency to make sure it do not harm too much the 2 chiplets SKU.
Yes, between the 8 cores per chiplet, the ipc increase from the new architecture, and the clock speed bump from the node improvements....I honestly believe that Ryzen4000/Zen3 will offer at least a 20% increase in performance core for core....and I plan on upgrading my 2700x to atleast the 4700/4800x, but maybe 12 or 16 core.
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#13
Turmania
I see they use parts that probably was not too good to fit in 3700/3800x versions, I get that and from profit side of things it makes a lot of sense. But I do wonder, if these not so good broken chips will let users down when they buy it and start using it.. afterall it is a defect product.
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#14
hat
Enthusiast
Turmania
I see they use parts that probably was not too good to fit in 3700/3800x versions, I get that and from profit side of things it makes a lot of sense. But I do wonder, if these not so good broken chips will let users down when they buy it and start using it.. afterall it is a defect product.
This is nothing new. Even as far back as socket 478, Celerons were Pentiums with defective L2 cache. I'm sure it goes back long before that.
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#15
candle_86
hat
This is nothing new. Even as far back as socket 478, Celerons were Pentiums with defective L2 cache. I'm sure it goes back long before that.
it does in need, 486SX was a 486DX that had a defective Floating Point unit
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#16
Dyatlov A
I will change my 3600X to this 3300X if core performance will be better.
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#17
primetime
Dyatlov A
I will change my 3600X to this 3300X if core performance will be better.
I think you be keeping what you have then
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#18
hojnikb
The real question is how these two cpus performn compared to the cheaper 1600AF?
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#19
Chrispy_
hojnikb
The real question is how these two cpus performn compared to the cheaper 1600AF?
I suspect the AF will do better, the same way that the 2600 is beating 7700K chips in almost everything, despite the IPC and clockspeed disadvantage (I said 2600 because the 1600AF is Zen+ IIRC)

Clockspeed is useful, but we're genuinely at a point where a lot of stuff now uses 8 threads or more. The difference between SMT and another real core is starting to get too big for the 4C/8T chips to hang with the pack. 4C/4T stuff is starting to bottleneck even moderate GPUs now, and 2C/4T is dead to me for anything that isn't effectively a webtop/netbook.
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