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AMD 7950X3D: Why doesn't AMD just put 3D V-Cache on both CCDs?

So I'm out here watching 7950X3D reviews and how AMD is doing some funky stuff to make sure that the 3D V-Cache CCD is only active while gaming to boost performance. And then it suddenly hit me:

Why not just put 3D V-Cache on the other CCD?

Yeah I know. The Cost will have to go up and it'll probably have some other funky stuff like having to be two separate NUMA nodes or something like that. But wouldn't performance in well multi-threaded games go up? Not to mention any need for using Game Bar or whatever will be gone. I'm probably way in over my head with something like this, and there might be another good reason that there's only one CCD with 3D V-Cache.

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The number of games that can take advantage of more than 8 cores—to make more than 8 cores with 3DVC worth it—is probably too small. So you wouldn't really benefit from it. It would increase cost for no benefit. It's likely also an issue with cross-CCD communication, where the advantage of more cache would be offset by the latency introduced by communication across CCDs.

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You'd make the clocks for the other CCD as slow as the one with the current extra cache. Without the extra cache the CCD can go up to 5.7GHz stock, the one with the cache tops out at ~5.2GHz, so for tasks where the extra cache isn't relevant, but the extra clocks is, you'd be having a worse processor compared to the regular 7950x.

 

The 7950x3D is basically a middle ground between a pure gaming CPU and a pure productivity one.

 

16 minutes ago, Epic_Busta said:

But wouldn't performance in well multi-threaded games go up?

No, the performance difference from a 7600x to a 7950x is pretty close to nothing, and you'd want to avoid switching data across CCDs anyway since that incurs some latency, so keeping everything in a single CCD with 8-cores and extra cache is best for games, while you can still have other higher-clocking cores for other tasks.

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Not to mention: with 3D cache on both CCD's, AMD can only make half the amount of 7950X3D CPU's. Meaning they make less money 🙄

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if your thinking of 3D cache for a gaming build later plus some work on the side then the 7800X3D is looking very much to be the best option.

For gaming no weirdness required just balls to the wall as it only has the one ccd to put the cache upon and its overall speed for regular workloads outside of gaming is decent compared to everything else just released and very fast compared to anything older.

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TLDR According to GN; The Cached CPU cores have to have their clocks reduced. Putting 3D cache on both cores could result in worse performance in non-gaming applications over the less expensive 7950X

 

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Ah, I suppose the mixed use argument by @igormpand @TVwazhere makes the most sense here. I initally took it mostly from a pure gaming perspective since 3D V-Cache is generally aimed at gamers, but glossed over other use cases. Not to mention there's been no media coverage of the lower end v-cache SKUs (that I know of, maybe I'm a touch out of the loop). The lower ends SKUs of the V-Cache line will probably be more enticing to people building gaming rigs in terms of value.

 

2 hours ago, johnno23 said:

if your thinking of 3D cache for a gaming build later plus some work on the side then the 7800X3D is looking very much to be the best option.

For gaming no weirdness required just balls to the wall as it only has the one ccd to put the cache upon and its overall speed for regular workloads outside of gaming is decent compared to everything else just released and very fast compared to anything older.

 Ah I'm probably not going to upgrade anytime soon. My overclocked 6700k is still going strong!

I appreciate everyone's responses! Especially as my first post on the LTT forum 🙂

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16 minutes ago, Epic_Busta said:

Ah, I suppose the mixed use argument by @igormpand @TVwazhere makes the most sense here. I initally took it mostly from a pure gaming perspective since 3D V-Cache is generally aimed at gamers

The 7950x3D makes no sense for use only with games, almost everyone agrees that it's better to wait for the 7800x3D. That's also likely the reason why AMD delayed its launch, since it'd eat away the sales of its more expensive sibilings.

17 minutes ago, Epic_Busta said:

Not to mention there's been no media coverage of the lower end v-cache SKUs (that I know of, maybe I'm a touch out of the loop). The lower ends SKUs of the V-Cache line will probably be more enticing to people building gaming rigs in terms of value.

7800x3D will be a thing in a couple weeks, but I doubt anything lower will become available, otherwise there'd be almost no reason to buy anything more expensive. Think of how the 5800x3D already made it hard to justify a 7000 series just for games, it'd be the same scenario all over again.

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