Info 64MB V-Cache on 5XXX Zen3 Average +15% in Games

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Vattila

Senior member
Oct 22, 2004
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Note that 5600X3D is reported/rumored to only add 32MB, so only half of the v cache. If true it's pretty much the dumping ground for all X3D dies where parts of the v cache broke, but at least half of it was still salvageable.
That is the only scenario that makes sense, as far as I can see. I have a hard time imagining AMD would stack perfectly good 64 MB V-Cache chiplets on top of salvaged 6-core CCDs. They must have built up such an inventory of partially faulty V-Cache chiplets that makes salvaging them worthwhile. However, that in turn means that the rumoured 12-core 5900X3D will most probably have two salvaged V-Cache chiplets stacked on top of two salvaged 6-core CCDs, for a total of 32 + 32 = 64 MB of V-Cache, and a total of 128 MB of L3 cache (64 MB on CCDs + 64 MB on V-Cache chiplets) — assuming all the salvaged V-Cache chiplets have half the capacity (i.e. 32 MB).
 
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Mopetar

Diamond Member
Jan 31, 2011
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That's a pretty good use case. Heavy multi-taskers.
In theory it should be good at that. It's basically the same use case as cloud computing where different applications are being loaded and unloaded, but it's hard to quantify for a consumer. The use pattern is likely more sporadic and it's hard to say if it makes a noticeable difference. I don't think anyone even has a benchmark that aims to test something like this.
 

Topweasel

Diamond Member
Oct 19, 2000
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That is the only scenario that makes sense, as far as I can see. I have a hard time imagining AMD would stack perfectly good 64 MB V-Cache chiplets on top of salvaged 6-core CCDs. They must have built up such an inventory of partially faulty V-Cache chiplets that makes salvaging them worthwhile. However, that in turn means that the rumoured 12-core 5900X3D will most probably have two salvaged V-Cache chiplets stacked on top of two salvaged 6-core CCDs, for a total of 32 + 32 = 64 MB of V-Cache, and a total of 128 MB of L3 cache (64 MB on CCDs + 64 MB on V-Cache chiplets) — assuming all the salvaged V-Cache chiplets have half the capacity (i.e. 32 MB).
I think that makes assumptions about the manufacturing process that may or may not be the case. It's entirely possible that AMD has to make decisions on manufacturing before knowing the status of the cache. It may be why AMD didn't do one of their two die chips as part of the project. It could be a combination of them disabling the cores because they have to disable cache because of cores or vice versa.
 

SteinFG

Member
Dec 29, 2021
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That is the only scenario that makes sense, as far as I can see. I have a hard time imagining AMD would stack perfectly good 64 MB V-Cache chiplets on top of salvaged 6-core CCDs. They must have built up such an inventory of partially faulty V-Cache chiplets that makes salvaging them worthwhile. However, that in turn means that the rumoured 12-core 5900X3D will most probably have two salvaged V-Cache chiplets stacked on top of two salvaged 6-core CCDs, for a total of 32 + 32 = 64 MB of V-Cache, and a total of 128 MB of L3 cache (64 MB on CCDs + 64 MB on V-Cache chiplets) — assuming all the salvaged V-Cache chiplets have half the capacity (i.e. 32 MB).
This is unlikely. AMD uses Chip-on-Wafer for 3D cache, so they grab a whole CCD wafer and place a lot of Cache chiplets on top. With this, they can choose what cache chiplets to put on, but can't choose CCDs (since they're a whole wafer).

Honestly I can't see them releasing more X3D variants for AM4.
 
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DrMrLordX

Lifer
Apr 27, 2000
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Why not now?
Just more upgrades for AM4 that are less likely to happen now that Raphael's release is pretty-much known.

It's going to be even more annoying if AMD launches a 7800X3D later this year and a 7900X3D in like April 2023. All the people that buy a day-one 7950X will be wondering if they should have waited . . .
 

moinmoin

Diamond Member
Jun 1, 2017
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However, that in turn means that the rumoured 12-core 5900X3D will most probably have two salvaged V-Cache chiplets stacked on top of two salvaged 6-core CCDs, for a total of 32 + 32 = 64 MB of V-Cache, and a total of 128 MB of L3 cache (64 MB on CCDs + 64 MB on V-Cache chiplets) — assuming all the salvaged V-Cache chiplets have half the capacity (i.e. 32 MB).
5900X3D is reported/rumored to contain 192MB of L3$ though, so it would be the new (and likely very last) marquee product for AM4.
 
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DrMrLordX

Lifer
Apr 27, 2000
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I'm guessing those type of people won't mind buying a X3D variant as an additional machine. I mean, it's not like normal people save up to buy a 5950X.
Personally I don't want both a 7950X and 7900X3D or whatever it is they call it. I'll probably want the 3D cache chip. Might have to wait a few months to see what AMD launches.
 

LightningZ71

Golden Member
Mar 10, 2017
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My thoughts on this are somewhat on a different track. The 5800x3d suffers from limited boost frequency because of a combination of package thermals and total power draw. The 5600x3d, with only half the stacked cache powered and two less cores to draw power may actually outboost the 5800x3d by a nontrivial margin in the same power envelope if AMD relaxes the limits that are on the 5800x3d. It might have better performance on a few games over the 58x3d. Also, from a total cache per core perspective, it doesn't suffer as much compared to the 58x3d as it has about 10.08 MB per core compared to 12MB per.

The 5900x3d is a different animal. It's going to have a massive 16MB of L3 per core and should only loose 100-200MHZ all core boost to the 5800x3d in the same power/thermal envelope. It should have a significant MT throughput advantage over the 58x3d and might surprise against the regular 5900x. If boosting behaves properly, it should be every bit as good as the 58x3d in almost all games with sane code and modest threading.
 
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Thunder 57

Golden Member
Aug 19, 2007
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My thoughts on this are somewhat on a different track. The 5800x3d suffers from limited boost frequency because of a combination of package thermals and total power draw. The 5600x3d, with only half the stacked cache powered and two less cores to draw power may actually outboost the 5800x3d by a nontrivial margin in the same power envelope if AMD relaxes the limits that are on the 5800x3d. It might have better performance on a few games over the 58x3d. Also, from a total cache per core perspective, it doesn't suffer as much compared to the 58x3d as it has about 10.08 MB per core compared to 12MB per.

The 5900x3d is a different animal. It's going to have a massive 16MB of L3 per core and should only loose 100-200MHZ all core boost to the 5800x3d in the same power/thermal envelope. It should have a significant MT throughput advantage over the 58x3d and might surprise against the regular 5900x. If boosting behaves properly, it should be every bit as good as the 58x3d in almost all games with sane code and modest threading.
I honestly don't see AMD releasing those parts.
 

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