(arstechnica.com)
Meanwhile I hope my AM4 will chug along a few more years.
You can buy 128GB of DDR5-6000 with a 9950X3D (not this newest X2 version, but still a $699 CPU) and a motherboard and a case for $2800 right now: https://www.newegg.com/Product/ComboDealDetails?ItemList=Com...
If you don't need 128GB, there are quality 64GB kits for under $700 on Newegg right now, which is cheaper than this CPU.
If someone needs to build something now and can wait to upgrade RAM in a year or two, 32GB kits are in the $370 range.
I don't like this RAM price spike either, but in the context of building a high-end system with a 16-core flagship CPU like this and probably an expensive GPU, it's still reasonable to build a system. If you must have 128GB of RAM it can be done with bundles like the one I linked above but I'd recommend waiting at least 6 months if you can. There are signs that prices are falling now that panic-buying has started to trail off.
128GB of RAM should not cost $4K even in this market.
Last summer, a 9950X3D + motherboard + cooler + 128 GB DRAM + VAT sales taxes was the equivalent of $1400 in Europe, where I live.
That's half of your quoted price. That was without case and PSU, but adding e.g. $200 for those would not change much.
The RAM price was already inflated at that time, and the same kit is now £800, but in October or earlier last year I'd have saved possibly the cost of the CPU/GPU on the whole thing, but now it's be about the cost of a CPU/GPU more expensive.
On a side note for anyone not aware, 9950X3D isn't the best choice for pure gaming, 9850X3D is cheaper and marginally better, also I went with 2 sticks of RAM kit, 4 sticks is much harder to run at the advertised speed (6000) which is actually an overclock.
Im a dev and a linux user/gamer hence my choice of CPU/GPU.
I don't really want to run my RAM that slow which is why I'll probably stick with two sticks.
I commented because someone thought that $4K was the going price for 128GB of RAM, which is way too much even with the demand crunch.
In January I was forced to upgrade an ancient Intel NUC, by replacing it with an Arrow Lake H based ASUS NUC. The complete system with 32 GB DRAM and 3 TB SSDs has cost EUR 1200, including VAT sales tax.
The distribution of the price was like this:
Barebone mini-PC: 41%
32 GB DDR5 SODIMMs: 26%
2 TB PCIe 5.0 SSD: 24%
1 TB PCIe 4.0 SSD: 9%
Before 2026, for so small amounts of memory its cost would have been much less than the rest of the system.
6 or so weeks after I returned it the kit was listed at 1499.
The most I could get running on 10GB VRAM + 96GB RAM was a REAP'd + quantized version of MiniMax-M2.5
It's so bad. I don't get why they sell AM5 motherboards with 4 RAM slots.
At least that system has been running well for like two years. But had I known that the situation is so much more dire than with DDR4, I would've just gotten the same amount of RAM in two sticks rather than four.
Some motherboards have it off by default.
This is my first time off intel and I have to say I don’t understand the hype.
The long POST times must mean it's retraining the memory each time, which is not normal. Just in case you haven'ttried it yet, I'd start by reseating them, I've had weird issues with marginally seated RAM before.
Also you definitely have to go much slower with 4 sticks compared to two, so lower speed as much as you can. If that doesn't help, I'd verify them in pairs.
If they work in pairs but not in quad at the slowest speed, something is surely wrong.
Once you get them working in quad, you can start bumping up the speed, might need voltage boost as well.
Cheapest 64GB kit is $930.
The kit I was oh-so-close to buying was two 6400 64GB sticks.
Not gonna buy now, not that desperate. I have a spare AM4 board, DDR4 memory and heck even CPU, I'll ride this one out. Likely skip AM5 entirely if something doesn't drastically change.
That's not far from the bundle deal above, once you subtract the $700 CPU.
If you really need 128GB the 5600 kit is fine. Having 208MB of total cache on the CPU means the real world difference between a 5600 kit and a slightly faster kit is negligible in most use cases.
If you don't need to upgrade then clearly don't force an upgrade right now. I just wanted to comment that $4K for 128GB of RAM is a very bad price right now, even with the current situation.
Does that “most use cases” caveat really apply to someone buying 128G of RAM? If I’m buying that much, it means I’m actually going to put it through its paces, unless it’s just there for huge reserved guest VM overhead.
If you’re trying to run LLMs off of the CPU instead of the GPU then the RAM speed dictates a lot. It’s going to be slow mo matter what, though. Dual channel DDR5 just isn’t enough to run large LLMs that start to fill 128GB of RAM and the difference between 5600 and 6400 isn’t going to make it usable.
If you’re just running a lot of VMs or doing a lot of mixed tasks that keep a lot of RAM occupied then you’d probably have a hard time measuring a difference between 5600 and 6400 if you tried with one of these X3D CPUs with a lot of cache.
This is a frequent topic of discussion for gamers because some people obsess over optimizing their RAM speed and timings and pay large premiums for RAM with CAS latency of 28 instead of 36. Then they see benchmarks showing 1-2% differences in games or even most productivity apps and realize they would have been better spending that extra money on the next faster GPU or CPU or other part.
Oh absolutely. Just mentioned it since I was very close to buying it back then, and now it's completely bonkers.
That bundle deal is quite well priced all things considered, it basically prices the memory where it was. Again, sadly no great bundle deals here.
I would not be surprised if we see casualties in adjacent markets, such as motherboards, coolers and whatnot.
Just reading now that they went out of production half a year ago which is a shame. I was very impressed being able to upgrade with the same motherboard 6 years down the line.
Other than the speed it’s a very good reason to go with amd, the upgrade scope is massive, on am5 you can go from a 6 core and soon all the way to a 24 core with the new zen6
Here's hoping to more developments like TurboQuant to improve LLM memory efficiency.
Su said that typically, the first quarter (Q1) is slower due to seasonal patterns, but AMD has seen its data center business expand from Q4 into Q1, demonstrating ongoing strength across both CPUs and GPUs. This growth underscores the company’s ability to capitalize on rising demand for AI compute and enterprise workloads, even during traditionally quieter periods.
“We are going into a big inflection year here in 2026. The CPU business is absolutely on fire.”
[1]: https://stocktwits.com/news-articles/markets/equity/amd-ceo-...
(cheapest at $1240 USD)
Nah, those of us who already bought DDR5 memory also already bought decent CPUs. Dropping another $1k for these incremental gains would be silly. It'd make a lot more sense if DDR5 had been around longer so that people had the option to make generational upgrades to this CPU but DDR5 on AMD has only been around for Zen4 and Zen5.
I hope this is still enough for the planned upgrade to Zen7 in 2028.
I really want to see what enabling the L3 cache options in the BIOS do from a NUMA standpoint. I have some projects I want to work on where being able to even just simulate NUMA subdivisions would be highly useful.
While I was aiming at 128, I settled for 96GB, because any more than 2 sticks means a sharp drop in RAM clocks this generation.
Feeling pretty chuffed now XD (though still sad because building a new PC is dumb when RAM costs more than a 24 core monster CPU)
The not so good side is that getting a RVA23 development board this year with an usable size of RAM (for e.g. compiling and linking large code bases) is not going to be cheap.
I am fine with my 2 year old 128GB DDR4 for now. I will just upgrade the 14700K to 14900KS CPU and wait 2 more years.
Judging by the benchmarks newer CPUs aren't much better for multithreading workloads than 14900KS anyway, so it doesn't make a lot of sense to upgrade to newer CPUs, DDR5 and a new mobo.
It was an expensive mistake as I bought a few options to experiment including a NUC and an M4 Mac Mini but eventually bought a 9800X3D 5070Ti PC for <$2 and for no reason in particular I bought a 64GB DDR5-6000 kit for $200 in August or so. I checked recently and that kit is pushing $1000. I also bought a 4080 laptop and bought a 64GB kit and an extra SSD for it too last year.
That's pretty lucky given what's happened since. I don't claim any kind of foresight about what would happen.
I do kind of want to take the parts I have and build another AM4 PC. The 5900XT is not a bad option with 16 cores for ~$300 but my DDR4 RAM is almost useless because the best deals now are for combos of CPU + motherboard + RAM at steep discounts.
You can get some good deals on prebuilts still. Not as good as 6+ months ago but still not bad. Costco has a 5080 PC for $2300. There's no way I'm going overboard and building a 128GB+ PC right now.
I've seen multiple RAM spikes. We had one at the height of the crypto hysteria IIRC but this is significantly worse and is also impacting SSDs. I kinda wish I'd bought 1-2 4TB+ SSDs last year but oh well.
We're really waiting for the AI bubble to pop. Part of me think sthat'll be in the next year but it could stay irrational substantially longer than that.
I upgraded my UPS to a sine interactive unit to minimise the risk of it dying to bad power while the market is so crazy...
It's probably not possible architecturally, but it would be amusing to see an entire early 90's OS running entirely in the CPU's cache.
I imagine for such a workload you can always solder a small memory chip to avoid having to waste L3 on unused memory and a non-standard booting process so probably not.
Lots of optimizations happening to make a trading model as small as possible.
The membrane keyboard wasn’t great (the lack of a space bar was a wierd choice) but it did work. We had programs on casette and did get the 16Kbyte memory expansion.
https://en.wikipedia.org/wiki/Timex_Sinclair_1000
I didn’t realize the Atari 2600 had basic, always thought of it as a game console.
Edit: Also this 192MB of L3 is spread across two Zen CCDs, so it's not as simple as "throw it all in L3" either, because any given core would only have access to half of that.
Nice demo, bad model. The funny part is that an entire OS can fit in cache now, the hard part is making the rest of the system act like that matters.
* https://en.wikipedia.org/wiki/Commodore_PET
Same time as the Trash-80 and BBC micro were making inroads.
There’s actually already two running (MINIX and UEFI), and it’s the opposite OS amusing - https://www.zdnet.com/article/minix-intels-hidden-in-chip-op...
If you run a VM on a CPU like this, using a baremetal hypervisor, you can get very close to "everything in cache".
Consider a VM where that kind of stuff has been removed, like the firecracker hypervisor used for AWS Lambda. You're talking milliseconds.
The lower leakage currents at lower voltages allowed them to implement a far more aggressive clock curve from the factory. That's where the higher allcore clock comes from (+30W TDP)
I'm not complaining at all, I think this is an excellent way to leverage binning to sell leftover cache.
Though if I may complain, Ars used to actually write about such things in their articles instead of speculate in a way that suspiciously resembles what an AI would write.
It depends on the task. For some memory-bound tasks the extra cache is very helpful. For CFD and other simulation workloads the benefits are huge.
For other tasks it doesn't help at all.
If someone wants a simple gaming CPU or general purpose CPU they don't need to spend the money for this. They don't need the 16-core CPU at all. The 9850X3D is a better buy for most users who aren't frequently doing a lot of highly parallel work
If your tasks don’t benefit then don’t buy it.
But stop claiming that it doesn’t help anywhere because that’s simply wrong. I do some FEA work occasionally and the extra cache is a HUGE help.
There are also a lot of non-LLM AI workloads that have models in the size range than fit into this cache.
See https://www.phoronix.com/review/amd-ryzen-9-9950x3d-linux/10
> Here is the side-by-side of the Ryzen 9 9950X vs. 9950X3D for showing the areas where 3D V-Cache really is helpful:
Coincidentally, it looks they filtered to all benchmarks with differences greater than 2%. The biggest speedup is 58.1%, and that's just 3d vcache on half the chip.
I’m curious to see whether the same benchmarks benefit again so greatly.
So for 9950X3D half of the cores use a small L3 cache.
For applications that use all 16 cores, the cases where X3D2 provides a great benefit will be much more frequent than for a hypothetical CPU where the same cache increase would have been applied to a unified L3 cache.
The threads that happen to be scheduled on the 2nd chiplet will have a 3 times bigger L3 cache, which can enhance their performance a lot and many applications may have synchronization points where they wait for the slowest thread to finish a task, so the speed of the slowest thread may have a lot of influence on the performance.
Agree. The article's 2nd para notes "AMD relies on its driver software to make sure that software that benefits from the extra cache is run on the V-Cache-enabled CPU cores, which usually works well but is occasionally error-prone." - in regard to the older, mixed-cache-size chips.
> I'm curious to see...
Yeah - though I don't expect current-day Ars Technica will bother digging that deep. It could take some very specialized benchmarks to show such large gains.
How critical of the lazy writers I am may seem outsized, but I grew up reading and learning from the much better version of Ars -one I used to subscribe to.
I might even shell out for an upgrade to AM5 and DDR5. On the other hand, my 5900X is still blazing fast.
For comparison, 9950X3D have a total cache of 144MB.
It is indeed 8MB per compute die but really 1MB per core. Not shared among the entire CCD.
And that answer is good enough for most workloads. You should stop reading now.
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The complex answer is that there is some ability one CCD to pull cachelines from the other CCD. But I've never been able to find a solid answer for the limitations on this. I know it can pull a dirty cache line from the L1/L2 of another CCDs (this is the core-to-core latency test you often see in benchmarks, and there is an obvious cross-die latency hit).
But I'm not sure it can pull a clean cacheline from another CCD at all, or if those just get redirected to main memory (as the latency to main memory isn't that much higher than between CCDs). And even if it can pull a clean cacheline, I'm not sure it can pull them from another CCD's L3 (which is an eviction cache, so only holds clean cachelines).
The only way for a cacheline to get into a CCD's L3 is to be evicted from an L2 on that core, so if a dataset is active across both CCDs, it will end up duplicated across both L3s. Cachelines evicted from one L3 do NOT end up in another L3, so an idle CCD can't act as a pseudo L4.
I haven't seen anyone make a benchmark which would show the effect, if it exists.
When the L3 sizes are different across CCDs the special AMD driver is needed to keep threads pinned to the larger L3 CCD and prevent them from being placed on the small L3 CCD where their memory requests can exploit the other CCD's L3 as an L4. The AMD driver reduces CCD to CCD data requests by keeping programs contained in one CCD.
With equal L3 caches when a process spills onto the second CCD it will still use the first's L3 cache as "L4" but it no longer has to evict that data at the same rate as the lopsided models. Additionally the first CCD can use the second CCD's L3 in kind reducing the number of requests that need to go to main memory.
The same sized L3s reduce contention to the IO die and the larger sized L3s reduce memory contention, it's a win-win.
https://www.phoronix.com/review/amd-3d-vcache-optimizer-9950...
For gaming, AMD already pins the game threads to the CCD with the extra cache pretty well.
For multi-threaded workloads the gain from having cache on both CCDs is quite small.
There are many applications which need synchronization between threads, so the speed of the slowest thread has a disproportionate influence on the performance.
In such applications, on X3D2 the slowest thread has a 3 times bigger cache on an X3D2 vs. X3D. That can make a lot of difference.
So there will be applications with no difference in performance, but also applications with a very large difference in performance, equal to the best performance differences shown by X3D vs. plain 9950X.
Now, would I upgrade an existing computer with a slightly slower processor with it, probably not.
If they are stacked then why not 9800X3D2?
Would be neat to have an additional cache layer of ~1 GB of HBM on the package but I guess there's no way that happens in the consumer space any time soon.
But to do it literally - I'm not a low-level motherboard EE, but I'd bet you're looking at 5 to 7 figures (US $) of engineering work, to get around all the ways in which that would violate assumptions baked into the designs of the CPU, support chips, firmwares, etc.