Friday, September 27th 2024

AMD Ryzen 9 9950X3D and 9900X3D to Feature 3D V-cache on Both CCD Chiplets

Earlier this week, we got rumors that AMD is rushing in the Ryzen 7 9800X3D 8-core/16-thread "Zen 5" processor with 3D V-cache for a late-October debut. The 9800X3D succeeds the popular 7800X3D, and AMD probably hopes it will have a competitive gaming processor in time for Intel's Core Ultra 2-series "Arrow Lake-S" launch. In the previous article, it was reported that the higher core-count 9000X3D series processor models, the Ryzen 9 9950X3D and Ryzen 9 9900X3D, would arrive some time in Q1 2025, because it was reported that the chips have certain "new features" compared to their predecessors, the 7950X3D and 7900X3D. At the time, we even explored the possibility of AMD giving both 8-core CCDs on the processor 3D V-cache. Turns out, this is where things are headed.

A new report by Benchlife.info claims that the higher core-count 9950X3D and 9900X3D will implement 3D V-cache on both CCD chiplets, giving these processors an impressive 192 MB of L3 cache (96 MB per CCD), and 208 MB or 204 MB of "total cache" (L2+L3). The report also says that AMD is planning a Ryzen 5 9600X3D chip, its second attempt at taking on Intel's Core i5 lineup, following its very recent release of the Ryzen 5 7600X3D, which ended up 1-3% short of the Core i5-14600K in gaming workloads. There's no word on whether the 9600X3D will launch in October alongside the 9800X3D, or in Q1-2025 with the Ryzen 9 9000X3D series.
Documentation indicates that the max L3 cache is 96 MB, although the reference to SOC configuration leaves it unclear whether this is from 3DVCache, placed on top of the CCD, or otherwise.
The introduction of 3D V-cache on both CCDs of the 9950X3D and 9900X3D could be interesting, as both chiplets will be capable of gaming workloads at a uniform performance level. On the 7950X3D and 7900X3D, OS scheduler-level QoS logic ensure gaming workloads are scheduled to the CCD with the 3D V-cache, while multithreaded productivity workloads are allowed to spread across both CCDs.
Source: Benchlife.info
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75 Comments on AMD Ryzen 9 9950X3D and 9900X3D to Feature 3D V-cache on Both CCD Chiplets

#1
Crackong
Finally, as it should've been.

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#2
usiname
Finally, now the people will see that the 3D cache on both dies is useless and will stop crying for this
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#3
Daven
My work is assigning me CAD and rendering work. So I guess I’m upgrading my 7700x to a 9950x3d on my gaming rig. Thread assignment won’t be an issue if both CCDs have 3D cache.

Adobe Dimensions and Solid works needs some fast PC specs. I have a 7900xt so GPU spec is already there.
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#4
Steevo
Sounds like my next upgrade.
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#5
napata
I wonder how much it'll add to the price.
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#6
Daven
usinameFinally, now the people will see that the 3D cache on both dies is useless and will stop crying for this
I guess you’ve never heard of thread scheduling and how hit or miss it is. This solves that problem. Even better if clock speeds can also be higher.
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#7
kondamin
napataI wonder how much it'll add to the price.
Depends on how arrow lake performs.
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#8
tfdsaf
AMD needs to lower prices on the new 9000 series CPU's, period. They are just not value oriented enough and are way too expensive for what they bring to the table compared to AMD's own 7000 series and the Intel 13k series. Intel is offering 14 cores for as cheap as $300, while AMD are stuck with 6 cores at those prices, its absurd.

The 9600x is $280 for 6 cores and barely 3-4% improvement in gaming over the 7600x, around 9% improvement in multithreading, while Intel's 14600 offers 14 cores for $260. Its around 15% faster over the 9600x in multithreaded apps and offers similar gaming performance.

Thing is the 9600x should cost $230 at most, with the 7600x starting at $200 and the 7600 vanilla at $180. The 9700x trades blows with the 14600k in terms of gaming, but falls short in multithreading, while being $70 dollars more.
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#9
Chaitanya
usinameFinally, now the people will see that the 3D cache on both dies is useless and will stop crying for this
There are plenty tasks besides gaming that will take advantage of that victim cache. Also now that both dies are getting stacked cache, it should get rid of problem arising from assymetric cores.
www.phoronix.com/review/amd-5800x3d-linux/3
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#10
john_
AMD could call the dual CCD chips EPYC 9900X3D and EPYC 9950X3D and not be far from the truth. So much cache on those chips in the past was only available in server chips.
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#11
persondb
Did they get around the clock speed regressions from 3D cache? That was essentially why they haven`t done dual 3D cache,

A lot of applications suffered more from the clock speed regression than the benefits of more cache.
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#12
Prima.Vera
What happened to the 8xxx series? Why the jump from 7 to 9??
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#13
dgianstefani
TPU Proofreader
Prima.VeraWhat happened to the 8xxx series? Why the jump from 7 to 9??
laptop APUs
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#14
_roman_
usinameFinally, now the people will see that the 3D cache on both dies is useless and will stop crying for this
I disagree. This should improve a bit the problem of wrong threads on the wrong core.

Amd should market those processors as EPIC and make them drop in replacement cpus for existing Consumer mainboards with X670 and similar chipsets.
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#15
Hardware1906
Prima.VeraWhat happened to the 8xxx series? Why the jump from 7 to 9??
8000 is for Desktop APU and Laptop
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#16
phanbuey
usinameFinally, now the people will see that the 3D cache on both dies is useless and will stop crying for this
I actually think with the inter-CCD latency at ~70ns this isn't far from the truth.
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#18
kondamin
Divide OverflowI look forward to TPU's review!
Yes and wondering where the lunar lake review is at
for some reason THG focused on gaming, because that's really what everyone is going to be doing on an ultra mobile device.
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#19
Blaeza
I'll pick up a 9800X3D in a year and a half, when you've all bug tested it for me. :nutkick:
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#20
john_
kondaminbecause that's really what everyone is going to be doing on an ultra mobile device.
No, it just that everyone wonders what the next Intel GPU will be offering. No one really cares about the AI capabilities or the plus 5% performance from the CPU. Everyone wants to know if Battlemage will be a small jump or a huge jump for Intel. It will also be an indication if AMD will have a strong competition in x86 handheld consoles.
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#21
AnotherReader
kondaminYes and wondering where the lunar lake review is at
for some reason THG focused on gaming, because that's really what everyone is going to be doing on an ultra mobile device.
Laptop reviews are, by definition, laptop reviews. Unlike desktops, where it's possible to standardize memory, power limits, and cooling, laptop CPUs are too dependent upon the OEM's configuration choices.
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#22
damric
This is a win.

As a plus side, these will be more energy efficient as they won't be clocked to the edge of silicon stability.

For those that don't need to cache, buy the regular 9950X.
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#23
usiname
DavenI guess you’ve never heard of thread scheduling and how hit or miss it is. This solves that problem. Even better if clock speeds can also be higher.
I guess you have never heard for the fix for the scheduling issue? Yes extra cache on both CCDs will make it more easy for the users, but it won't make it faster than 9800X3D, the reason why so many people whining for extra cache on the second CCD. Anyway, the increased price(if) compared to Ryzen 7000 is not justified if this will just fix something, that already can be fixed - the scheduling issue
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#24
AusWolf
usinameFinally, now the people will see that the 3D cache on both dies is useless and will stop crying for this
_roman_I disagree. This should improve a bit the problem of wrong threads on the wrong core.
Either scenario sounds plausible to me. It'll be interesting to see it in action. :)
Posted on Reply
#25
RogueSix
DavenI guess you’ve never heard of thread scheduling and how hit or miss it is. This solves that problem. Even better if clock speeds can also be higher.
It is quite the contrary to what you say. Scheduling will now be even more important to the point it becomes SUPER-DUPER-MEGA-EXTRA-important with cache on both CCDs. For this dual cache setup to work correctly, games/apps (via the scheduler) always need to request the cached data from the "correct" cache on the "correct" CCD or else you will suffer latencies from hell if/when data needs to be fetched from the cache across the CCDs because e.g. Core 3 requests data that was previously stored to the cache by Core 14 on the other CCD. Can't have a scenario like that. Ever.

So, both the scheduler and the CPU always need to "know" exactly "who" (which core) cached something (what) and where it was cached to avoid the dreaded inter-CCD and inter-cache latencies. This is definitely going to be a challenge and very complex on the level of correct scheduling and correct CCD assignment etc.

AMD does not exactly have the best track record when it comes to these scheduling and core assignment shenanigans so I would be quite surprised if they get this to work flawlessly out of the gate.
Personally, I have avoided multi CCD CPUs like the plague due to the Xbox GameBar and 'GameMode On' requirements (I have a PC and not a console, you muppets). It will be interesting to see if the GameBar requirement will be dropped now(?) since core parking will no longer be required.

We'll have to wait and see how well this is gonna work in practice. I would expect some growing pains, to say the least...
Posted on Reply
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Sep 27th, 2024 19:31 EDT change timezone

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