AMD Announces Ryzen 7800X3D / 7900X3D / 7950X3D Pricing & Availability

[Mark Rose]

That's not necessarily going to be better. Some workloads benefit from more cache, some benefit from higher clocks. They can't combine higher clocks with more cache at the same time if I understood correctly due to fact that cache silicon is stuck at certain size like memory in general and can't be switched to smaller process node so they need to limit the power usage there in some way.

AMD spoke before how logic circuits are shrinking, while some others like cache - already stopped because their density reached the limit.

For my workloads the extra cache is better. Both the applications I run and the games I play.

The mixed chip is acceptable for my application since DDR5 6000 would supply approximately enough bandwidth to keep 8 cores busy with AVX512 with my application. The other cores could work entirely out of the increased L3 cache on their chiplet.

I guess pinning the game threads to a core range works. I could run games through numactl or taskset. Kind of a pain.

The clock speed limit is likely a thermal limit. The cache will produce a good amount of heat, plus the heat below needs to pass through it to reach the cooler.

[shmerl]

Yep, if they could shrink the cache more, they could avoid this thermal issue while keeping core clocks high, but they can't shrink it further. That's the reason if I understood correctly why they avoided going for adding extra cache to all CCDs.

[polarathene]

The other thing to remember when comparing prices of the 7700 vs 7700X is that the former comes with a nice (for an OEM) cooler. The 7700X doesn't come with any cooler.

That's also a reason for me to prefer the 7700X actually. That stock cooler won't fit into my case (Phanteks Evolv Shift XT), while other air coolers can have compatibility issues with the ITX motherboard clearance issues. At the time when I bought the case on sale, I hadn't considered that problem so I'm limited to choices like an NH-L9x65, spending more on AIO, or getting a bigger case / mobo.

[horizonbrave]

[...] it appears there are no ethical manufacturers remaining.

What about Apple silicon?
If not ethical, at least (by name of it) it sounds organic.

[Mark Rose]

you'll end up with worse performance or at best, 10% better performance than a regular 7950x. back when amd launched the 5800x3d, amd-robert did an interview on a podcast talking about why they abandoned the 5900x3d. to do a long podcast short, having the large cache on both ccd's caused to many ccd to ccd infinity fabric talks because unless both caches can stay fully saturated, the one ccd with cache that is saturated will cross talk to the other ccd's cache that wasn't and try to draw from it. the only benefit came when both cache's were fully saturated and at most you saw a 10% increase. and gaming performance across the board was worse than the 5800x3d. it wasn't worth to release a product that more often than not, was slower. with having such a large cache on both ccd's the chances of both being fully saturated was slim in their findings. so that's why with zen 4 they went with the "lopsided" cache configurations. it will have a lower chance of infinity fabric ccd to ccd cache communication. couple that with windows application pinning to a ccd it will further help reduce it. which is also interesting because it does show there is a limit to cache sizes with multiple ccd's in use. to much cache can result in regressions.

that said, i wouldn't get either the 7900x3d nor the 7950x3d because its to much of a mess. linux or windows. i'm glad i maxed out my am4 board with my 5950x. i'm going to coast on that till zen 5.

I happen to have an application that fits in the larger cache. I could run two copies of it, one on both chiplets. I realize my situation is somewhat unique.

Good to know that gaming performance suffers though.

I think I found the interview you were referring to: https://www.youtube.com/live/ha_U8rr...e=share&t=1318

He's right that if you have two threads running on two chiplets accessing the same data performance will suffer. The way MOESI protocol in AMD CPUs works will result in a lot of data being bounced between chiplets unless it's shared. I imagine a single threaded game wouldn't be hurt as much as a multi-threaded game.

I thought about getting an entirely new 5800X3D system because the situation with 128 GB of memory is more stable. Though DDR5 6000 would have much better bandwidth for 8 Zen 4 cores, for my application. I wonder how stable 128 GB of DDR5 at 6000 MT on a 7800X3D will be.

[rhadlee]

Can’t fault them for maximising the commercial return from their CPUs.

Since these processors are gaming-oriented, I would be remiss for not pointing out that PC gaming is in a pretty tough spot right now. Hardware prices have skyrocketed. Meanwhile, consoles are more competitive than ever. Making matters worse, many PC ports are a crapshow of technical ineptitude. I simply don’t see a strong argument for PC gaming at the moment. Unless you are into PC-only genres like simulation games or esports titles. Neither of which needs a Ryzen 7000 X3D CPU by the way.

[ssokolow]

Depends on binning, maybe the 65W chips need more voltage to be stable, so the clock is lower..
Better chips = lower voltage and higher clock you can run them on, so less power consumption for more performance

I'm also generally stability minded to the point where I have a history of running things in stock configuration.

[CochainComplex]

That's cool and all, but those prices basically ensure that I'm gonna ride out AM4 for a while seeing as how the 5800X3D is $338 on Newegg at the time of this post. Their new shit needs to be a bit more competitively priced with their current shit.

I m having the same approach. Since i want to ride the AM4 board till its not upgradeable anymore. Why ultimately it would be the 5800X3D fo my usecase. but one has to consider that the 5800X3D is still highly priced because its one of the best gaming CPU yet. You can get a 5700X already for almost half of the price.or a simple 5800x for 2/3. And a simple 5600 is hovering almost around 1/3 of the 5800X3D.

Considering the current financial situation of a lot of people I'm not sure if the sales of the newer 7000 in combination with Board and New Ram will be as good as the marketing team might expect.

[Linuxxx]

yeah the 7900x3d and 7950x3d will be a complete shit show scheduler wise. And as you said it looks like Microsoft will simply make this a whitelisting thing in Windows 11. There will simply be no means for any scheduler to be able to determine if your thread would benefit from a larger L3 cache or a higher potential boost clock, also not to mention that what your thread would benefit from would change from time to time and moving the thread across ccd:s imposes a huge penalty.

It's kinda curious to see that AMD would go on to create an even bigger scheduling nightmare than Intel ever could with their hybrid x86 design.

Plus Intel atleast tried to mitigate the problem somewhat at the hardware level with their "Thread Director".

I wonder why AMD couldn't do something similar for their asymmetric 3D caches?

[Anux]

Those prices are to damn high!
cheapest AM5 board: 180€
slow 32 GB DDR 5 4800: 120€
and the 7800x3d probably around 550€

And the GPU world is even worse. Good thing is, I'm old n' grumpy, I can just wait ...