Reviews are out for the Ryzen 7950X3D, and it’s actually quite interesting. For those that don’t know, the X3D version of Ryzens include a very large amount of 3D V-Cache. In this instance, it’s 128MB of level 3 cache. However, there is an important catch that anyone looking at the 7950X3D as a gaming CPU should be aware off.
Only One CCD Has 3D Cache.
The 7950X3D is a 16-core CPU. However, those cores are divided between two CPU clusters or dies. These are physically separate from each other, but can talk through a dedicated bus call Infinity Fabric. In the case of the 7950X3D, only one of the CPU dies has the 3D V-Cache. The other die is a normal 8-core die that you would find on a regular 7950X.
What Does This Mean?
With only a single die having V-Cache it’s extremely important that the games that can take advantage of that cache run on that die. This doesn’t always happen and you can loose the performance advantages of the additional cache. While it’s not as bad as a game unintentionally running on the E-Cores (efficiency) of Intel’s 12th and 13th gen Core CPUs, it effectively negates and performance benefit you would get, and in some instances runs slower than a stock 7950X. As an example, Hardware Unboxed discovered that Tom Clancy’s Rainbow Six Extraction and Factorio both performed very poorly due to this issue during their testing.
Why Is This Happening?
All AMD CPU dies that use 3D V-Cache run at a slower clock speed than their non-V-Cache counterparts. There are myriad of technical reasons why, but the bottom line is that games and programs that rely on clock speed and not cache for performance can actually run worse. Additionally, some games just don’t benefit as much from the additional cache.
It Will Be Fixed with Drivers…Mostly.
Keep in mind that the issue will be addressed through driver updates. Gamers Nexus found that updating to the latest chipset drivers saw massive boosts in performance for their game tests. Shadow of the Tomb Raider improved by 35% with the new chipset drivers, and F1 2022 improved by 31%. CS GO and Rainbow Six Siege, both games that don’t heavily rely on V-Cache, saw a 3% and 6% uplift respectively in Gamers Nexus’ testing.
The reason for the uplift is that the drivers will actually park (aka idle or not use) the non-V-Cache cores when a game is detected. AMD ties into Windows Game Bar in order to do so. This is very similar to the first generation Threadripper “Game Mode”, albeit while still having those non-V-Cache cores ready for appropriate workloads. Additionally, the non-V-Cache cores can actually run at a higher clock speed than the V-Cache cores.
Put another way, your 7950X3D will only run the eight V-Cache cores while gaming.
Make no mistake, the 7950X3D and upcoming 7800X3D are going to be the fastest gaming CPUs until the next generation of CPUs are released. However…
You Need a Powerful GPU and…
There are two caveats to see the large uplifts that reviewers are seeing.
1. You need a very powerful GPU.
2. You need to run in low resolution with low to medium settings.
CPU reviews are almost always done at low resolutions and low settings with the most powerful video card available. This allows the CPU performance to become the bottleneck and not the GPU performance. Most reviewers will run games at 1080P or lower, and in low to medium settings on an RTX 4090. While I do know people who do competitive gaming at this resolution and settings combo, it’s not how most people play when they have that powerful of a GPU. Realistically, if you have a 4090 class GPU, you’re probably playing at 1440P or 4K these days. 1080P is still very popular but most people play with high or ultra settings if their GPU allows it. Doing so frees up the CPU bottleneck as more of the performance burden is placed on the GPU.
Don’t get me wrong. The CPU is still very important at even 4K Ultra settings. However, you will see diminishing returns. A good example of this shows up in Eurogamer’s testing. Metro Exodus Enhanced Edition performed only about 10% better on the Ryzen 7950X3D than it did on a Ryzen 5600X at 1440P. This was tested with an RTX 3090 which is still a very fast GPU by any measure.
Another example would be in Tech Power Up’s testing. They used an RTX 4090 at 4K Ultra settings across their entire benchmark suite. At those settings and resolution, the Ryzen 5600X was able to provide a suite average of 86.8% the gaming performance of the 7950X3D.
What About Power and Heat?
Well, I have some very good news for Small Form Factor enthusiasts; The 7950X3D is very efficient. Optimum Tech saw that the 7950X3D was only pulling 76 watts while playing Valorant, while Gamers Nexus found that it used 156 watts while performing a Blender Render on all 16 cores at 100% usage. This is substantially better and easier to cool than the 250 watts the original 7950X required while still providing nearly identical performance.
AMD has also lowered the 95C thermal limit of the Ryzen 7000 series to 89C for the 7950X3D. For those that don’t know, AMD has determined the temperature that the CPU will be allowed to rise to and maintain under load. In this instance, it’s 89C. Basically, the CPU will safely sit at 89C all day while working under load. To maintain that temperature, the CPU will automatically adjust voltage and clock speeds. The better the cooler, the easier it is to maintain that fixed 89C and the faster the CPU can run. This is why modern CPU reviews give a range for the CPU boost clock speeds as opposed to a fixed clock rate as in the past.
Is It Good for SFF?
Yes. Absolutely yes. The 7950X3D represents something great for SFF users who want a system with the fastest gaming CPU, and damn near the fastest production CPU. Gaming power draw was light and easily handled by most SFF air coolers, while production could be handled easily by quality 120mm based air coolers. A 240mm AIO would easily handle the 7950X3D.
My ideal build for this chip would be something akin to the Dan Case / Lian Li A4-H20. Pairing a 7950X3D with a 240mm AIO and a RTX 4090/4080 in that size of a case would be one hell of a build that would provide top tier performance in both gaming and production. Adding in one of the newer 96GB DDR5 kits would be icing on the cake.
Alternatively, if all you do is game, the upcoming 7800X3D would be the better choice. As games require less power than production workloads, and there are eight less cores, it will likely perform well even with an Noctua L12S or similar cooler. If the RTX 4070 series makes its way to ITX class GPUs, I would consider building a CCD MI-6 with it.
I’ve only touched on the details in this summary. All of the listed reviews below go into further details so makes sure you look at your individual work and gaming usages. Also, please show your support to the women and men who have spent countless hours benchmarking by checking out the reviews below, and subscribing to their YouTube channels.