AMD's Top of the Stack 3D V-Cache CPU Pushes Even the RTX 3090 to Its Limits
Saying that it has been a busy launch season for AMD is an incredible understatement. Not only did we see the release of the high powered, high performing Ryzen 7000X Series, but we also got a full stack of lower powered, but still respectably performant processors in the Ryzen 7000 Non-X Series. And let’s not forget a generational leap for Radeon GPUs!
In all of these releases, we have been waiting for AMD to juice up one of its Zen 4 juggernauts with that sweet, sweet game-changing 3D V-Cache we saw in the Ryzen 7 5800X3D. For the experts, the V-Cache stacks more memory on a chip vertically. For everyone else, number go up. What we’re getting is three options – the Ryzen 7 7800X3D, Ryzen 9 7900X3D, and Ryzen 9 7950X3D.
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Launching today (February 28th, 2023), the Ryzen 9 7900X3D and Ryzen 9 7950X3D are the first Ryzen 9 CPUs to get the V-Cache treatment. These CPUs are aimed at the gamer who also happens to be a content creator. There is a twist in that, but we’ll talk about it more later.
For this review, we got to check out the cream of the crop, the Ryzen 9 7950X3D–AMD’s 16-core, 32-thread monstrosity of a CPU.
What is 3D V-cache?
Before we can get into the performance, we have to take a look at pricing, the CPU design, what 3D V-cache is, how extra cache benefits gaming, and how the heck this thing even works! Let’s put the cache on the table first.
AMD’s 3D V-cache technology takes the existing Zen 4 cores, thins them down, and stacks an extra layer of L3 cache on top of the chiplet without increasing the overall Z (or vertical) height of the CPU. This design allows for a more dense connectivity between the CPU die and the cache, providing a faster memory resource than your garden variety system RAM.
In gaming, the extra cache helps the CPU in moments where quick access to random data is essential. For example, if you’re playing a match of Gambit in Destiny 2, your CPU doesn’t know if you are going to bank those motes like The Drifter is screaming about or if you are going to turn around and Thundercrash into an invading player. In other words, player-driven actions are random processes that require rapid computation. In that moment, your CPU is called upon to recall textures, animations, game physics, character placement, and more. When that happens, cache is king.
(You can find AMD’s breakdown of the technology here for a more detailed description.)
Moving on to pricing, AMD did something interesting here. At the top end of the Ryzen 7000 Series product stack, the Ryzen 9 7950X and 7950X3D are priced identically at $699 USD. Both CPUs are 16-core, 32-thread processors, but the 7950X trades 3D V-cache for overall faster base clock frequencies and a higher power draw to match. As things trickle down the stack, we start seeing a $50 USD difference between counterparts and a much slimmer margin of difference. Where the big difference lies is in the design.
The 7950X, 7900X, 7950X3D, and 7900X3D each have a core complex die (CCD) made up of two core complexes (CCX). The X3D processors also have two core complexes, but only one CCX is equipped with the 3D V-cache. AMD’s official word on this is that, in its testing, the company did not see a noticeable enough uplift in performance to justify the extra cost of putting it on both. Fair enough, but is Windows smart enough to know which cores to use for what?
Sort of, but I can only speak for the 7950X3D (while making some educated guesses on the 7900X3D). Because of this, the CPU is dependent on processes like the Game Bar to park the CCX without the V-cache while “whitelisting” or allowing gaming processes to access that CCX with the V-cache. The hit rate for the V-cache CCX can be negatively impacted if you have other background processes running. It will be interesting to see if this is the same with the 7800X3D once it releases.
Same Ryzen 7950X Hood, Slightly Different Hardware
The AMD Ryzen 9 7950X3D is a 16-core, 32-thread (16C/32T) CPU with a base clock speed of 4.2 GHz and max boost speeds up to 5.7 GHz. While the core and thread counts are the same as the Ryzen 9 7950X, the base clock is slightly (~300 MHz) slower. Base clock speed isn’t the only thing that’s lower, though, as the 7950X3D drops 50W off of the TDP, dropping the Ryzen 9 down from 170W TDP to 120W TDP. That means it draws less power.
At the same time, the 7950X3D has a 128MB L3 cache, double that of the 7950X.
Now, in all of this, the comparison between the Ryzen 9s does get a bit trickier. Remember, we have two CCX modules–one with the 3D V-cache and one without it.
There’s Always a Cache
Unfortunately, we’re going to be seeing the 7950X3D in isolation from the other X3D CPUs. For our purposes, we are going to show some comparisons with the current flagship CPUs from both sides of the aisle.
In our productivity tests, we used data from the entire Ryzen 7000 Series stack as well as Intel’s 13th Generation Core i5-13600K and Core i9-13900K. We also included data collected by Joanna Neilus from our Ryzen 9 5950X review as a reminder of how far things have advanced across a single generation.
In gaming, however, we narrowed the comparison to the current kings – the Core i9-13900K and the Ryzen 9 7950X. This data was collected utilizing as similar a testing environment as possible, but, as always, your mileage may vary.
As always, we tried to keep our methodology simple in order to give the clearest picture of the performance that the average user can expect to get out of the Ryzen 9 7950X3D. In other words, these numbers represent box-to-build performance with no tweaks. The only advantage we gave them is that we enabled an AMD EXPO profile for low memory latency and speed. We offered the same consideration to our Intel platform by enabling XMP.
Here is the hardware we used to collect our data from the Ryzen 7000 Series CPUs:
- Gigabyte X670E AORUS MASTER motherboard
- NVIDIA RTX 3090 Founders Edition GPU
- AMD Radeon RX 7900 XTX GPU
- 32 GB G.Skill Trident Z5 NEO DDR5-6000 RAM
- 2TB SK hynix Platinum M.2 NVMe SSD
- NZXT C1200 Gold 1200W power supply
- NZXT Kraken Z73 360mm all-in-one liquid cooler with three 120mm fans
- NZXT H9 Elite mid-tower PC case with two 140mm fans as well as three 120mm fans.
You may notice that we listed two GPUs in our test bench–there is a very good reason for that: we bottlenecked our RTX 3090 in our 1080p gaming test. We are going to include these numbers for comparison, but we went back and ran the same tests on the 7950X and 13900K using the Radeon RX 7900 XTX for a more accurate picture of performance overall. I know that sounds wild, but wait until you see the difference!
Does More Cache Equal More Productivity?
In our productivity tests, we ran a suite of software benchmarks to highlight single and multi thread performance in scenarios designed to test how each CPU performed under various computational loads.
Here is what we found:
In Geekbench 5, we calculate the performance of single thread tasks such as image and text compression, web navigation, machine learning, and .PDF rendering. In this benchmark, the Ryzen 9 7950X3D did put on a strong show, but slightly underperformed when compared to the 7950X and the 7900X. Even so, it still managed to edge out the Core i9-13900K by a slim margin in single core performance. These numbers, however, are within a close enough margin that I wouldn’t necessarily declare one of them a winner.
In multi core performance, this is where we see the 7950X3D lag a bit behind its counterpart from the Ryzen lineup while falling further behind the Core i9. It is possible the overall frequency and parked CPU cores could be causing this performance delta, or this could be a scenario where the extra cache just doesn’t hold any power. That being said, the 7950X3D delivers on its ability to be a strong contender in multi core tasks.
We see a similar story in Handbrake:
While rendering a 4K video down to 1080p30, the 7950X3D hangs closely with the 7950X while taking an 11 second lead ahead of the 7900X. It still trails behind the 13900K, but when you look across the landscape, the 7950X3D does well for itself.
That margin got a whole lot slimmer when rendering an image of everyone’s favorite, shiny red BMW in Blender. This image took the 7950X3D just over a minute to render, putting it within 3 seconds of the Core i9’s finishing time and 4 seconds away from the 7950X. Not too shabby at all!
Overall, we did not see an uplift in performance in our productivity benchmarks. However, whether V-cache was leveraged or not, the 7950X3D still performed well overall thanks to the powerful Zen cores.
3D V-cache in gaming
I’m not going to mince words: this is where things get weird.
When we started running the 7950X3D through our gaming tests, we wanted to keep our testing data similar to our most recent CPU reviews. So we used NVIDIA’s RTX 3090 Founders Edition in our testing bench, like before.
As we got into our benchmarking, we weren’t noticing a difference between it and the 7950X. Not only that, there were actually places where it underperformed. This was frankly disconcerting–especially after seeing what AMD’s 3D V-cache did for the 5800X3D.
It is important to mention that these tests were run at 1080p. While a GPU can impact performance at this resolution, there is much more of a burden on the CPU. Going even lower to 720p would have really pushed the CPU, but this resolution is largely irrelevant to the modern user outside of handhelds.
After doing some digging into the data and reaching out to AMD, we wondered if we were hitting a wall somewhere. As it turns out, we were. So, we brought in the Radeon RX 7900 XTX, and this is the difference we saw:
It would seem as though the 7950X and 7950X3D both benefited from some of the extra headroom that the 7900 XTX provided. In some cases, we saw a leap of 26% performance in frames per second after swapping GPUs! With that point discovered, we moved on to the rest of our gaming benchmarks.
In a number of our tests, we saw the Ryzen 9 7950X3D overshadow its non V-cache Ryzen counterpart. However, it didn’t quite beat out the Core i9-13900K in our tests.
Again, this was weird to me, so we did a bit more digging, and we think we have an answer.
We mentioned a few things earlier that need to be taken into account when looking at these numbers. Remember, the 7950X3D is a complex chip made up of two chiplets–one with the 3D V-cache, and one without. The V-cache can help with quicker computation of random player-driven actions, but performance utilizing the V-cache equipped core is dependent on the processes actually using those cores. This means some cores are parked while Windows sends tasks on to the V-cache equipped cores.
Before doing anything, we made sure that all the appropriate software and firmware were up to date. We also ensured that any extra background tasks were killed or completed before proceeding with collecting our data. After spending time running multiple benchmarks and monitoring the core performance, we saw a few benchmarks that either were not fully parking the non V-cache cores, or that needed us to force Windows Game Bar to whitelist a game.
Interestingly, this was the case for Far Cry 6 - an AMD partner title. There was a ~10% difference in performance after manually telling Windows Game Bar to remember the title. Before whitelisting, the average performance was ~181 frames per second, which, you may notice, falls shy of the 7950X. It was only after poking at Game Bar that we saw that number increase to 200 frames per second.
This wasn’t the only oddity, though. In our Metro Exodus benchmarks, we saw the non V-cache cores fighting to stay parked throughout the test. When we tried to force them to park, we did see an overall boost in frames per second, but the game’s performance was full of stuttering.
That being said, while running the 7950X3D outside of testing, I did not notice any stuttering in performance that I could attribute to the CPU. It performed well in tandem with both the RTX 3090 and Radeon RX 7900 XTX in everyday use, including gaming and light video production.
Ryzen 7950X3D Energy Efficiency and Thermal Performance
When the Ryzen 7000X3D CPUs were announced, one of the points that we noticed immediately on the product infographic was a lower overall TDP. Considering the leap we saw in power draw from both sides of the aisle and the performance of the Ryzen 7000 Series non-X CPUs, we were curious how a middle-of-the-road power draw would impact these CPUs.
Here is what we found:
In most of our benchmarks, the 7950X3D drew a significantly lower amount of overall power than the 7950X and the i9-13900K. On first glance, these numbers are pretty impressive, but these numbers might not be telling the whole story.
Remember: the 7950X3D parks some of its CPU cores while they are not in use. We did not observe whether or not that was the case with the other CPUs, so it’s hard to make a definitive statement here. However, if the 7950X3D is performing at a significantly lower power draw and hitting the numbers it is, I’d call that an overall win.
When it comes to thermal performance, things are spread out a bit.
In our productivity benchmarks, the 7950X3D stayed significantly cooler than the 7950X and the 13900K in some cases, but was still warmer than the Core i9. In gaming, there is a fair degree of competition across the board, but, overall, the 7950X3D kept the heat under control, thanks to NZXT’s Kraken Z.
It is also important to note that, while we try to keep our test environment as consistent as possible, the climate that I am testing in is fighting between being in the bowels of third winter and what we would call fool’s spring. Try as I may, keeping our test benches in a space that holds a comfortable 23.3C has been tricky.
A Cache-Conscious Conclusion
It is important to point out the purpose of the Ryzen 9 7950X3D while drawing our conclusions about it. This CPU in particular is meant for the gamer who also uses their rig for productivity purposes. When you’re trying to be a jack-of-all-trades, sometimes there are compromises or concessions you have to make.
When talking purely about performance, the 7950X3D hangs closely to its fellow Ryzen 9 in productivity, but lags slightly behind the competition. In gaming, when we see the V-cache at work, the uplift is fantastic. When it doesn’t quite hit on those CPU cores, it isn’t terrible, but it isn’t as impressive as it could be. This, however, could change as the software matures to support it.
We also need to talk for a moment about the GPU situation we ran into. Honestly, I was pretty stunned by this discovery. From one point of view, you could look at the 7950X3D as a powerful taskmaster, pushing last-gen juggernauts to their fullest potential. On the other side of this point of view, running anything less than an RTX 3090 would mean that the 7950X3D is not living up to its potential. The RTX 3090 is already more powerful than what most PC gamers on Steam are running, meaning that there’s a good chance your system isn’t strong enough to fully utilize the 7950X3D. If that’s the case, buying it might leave you with similar performance to a cheaper, lesser chip unless you go for costly upgrades to accompany it. Given how expensive and recent the RTX 3090 is, that’s asking a lot.
So, at $699 USD, is the Ryzen 9 7950X3D a good buy?
That answer depends on a few factors.
Are you looking for behemoth-like performance with no concern for power efficiency? The 7950X3D is powerful, but if you’re looking at dollar-to-performance, you should probably look elsewhere. Are you building a multipurpose rig with a high-end, current generation GPU and need a CPU to keep up with it? The 7950X3D would definitely fit that bill. Do you want to get every ounce of performance out of a last gen GPU with headroom for future growth? The 7950X3D could be pretty appealing here.
All of this comes with a huge caveat: we have yet to see how the Ryzen 7 7800X3D performs. Unfortunately, we will have to wait until April to find that out.
No matter what conclusion you draw from our testing and review, the Ryzen 9 7950X3D is a pretty impressive feat in its own right. AMD created a unified CPU die with asymmetrical chiplets and a healthy amount of cache. There is little doubt that this is a powerful CPU with room to grow.
Like any new leap in technology, there are going to be some hiccups along the way. Our hope is that, with some time and maturity, we will see the 7950X3D improve as more systems and software take advantage of the technology.
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