AMD Ryzen 9 7950X3D Review: AMD’s Answer to Raptor Lake

Today we look at the highly anticipated AMD Ryzen 7950X3D, which features AMD’s 3D stacked V-Cache technology first debuted on the 5800X3D. The technology in itself allows AMD to stack on an additional 64MB of L3 cache on the actual die of a CCX with through silicon vias (TSVs) for copper to copper contact, and in the case of the 7950X3D only one of the CCXs will be stacked with 3D V-Cache. The cache is made up of 13 copper and one aluminum layer. While the CCX has shrunk to 5nm, we are not exactly sure what process node the extra cache is; AMD says it is 7nm, but there are rumours of the process node for the cache being between 5nm and 7nm. With the 5800X3D things were pretty straight forward, there was only one CPU core complex, but with the 7950X3D there are two. AMD’s answer to that die was to slim the Z-height of the CCX and then add on a bunch of SRAM for the expanded cache, while utilizing software to determine when to only utilize that die.

The software is important. For starters, when a game is detected off of Microsoft’s Known Game List (KGL) through the XBOX Game Bar app, cores 16-32 will be parked. That means a whole CCX will be idle, and this is by design to avoid cache misses. The parked die will then be brought back when the game is out, and this die is the higher frequency die. The die with the 3D V-Cache doesn’t boost to 5.7GHz. The 3D V-Cache is sensitive, and AMD has decided to lock down manual overclocking on the CPU, leaving users with the option to use Curve Optimizer (CO) instead. You can lower settings like voltage, which is how Curve Optimizer works. On the X670E Ace motherboard we used, there was actually an Enhanced CO option, which would utilize CO curves, and that mode gave us much greater performance, but it wasn’t super stable. MSI told us it will vary from sample to sample, and they have different levels like one, two, and three. Let’s get to the benchmarks, because this CPU is actually impressive in games, while still productive in other things.

Test Setup:

All tests on all CPUs ran with XMP enabled 6000MHz and virtualized based security (VBS) disabled through the UEFI. Windows 11 22H2. You will also need to update your XBOX GAME BAR through this code run through command prompt: “cmd.exe /c start /wait Rundll32.exe advapi32.exe,ProcessIdleTasks” and it takes about 30 minutes to run. Intel’s Thread Director is now met with AMD’s 3D V-Cache and Provisioning driver, they do different things but achieve the same result, a more intelligent CPU.

CPU: 7950X3D, 7950X, 7900X, 13900K, 13600K

Memory: 32 GB (16GBx2) G.Skill Trident Z5 6000MHz

GPU: AMD Radeon 7900XT

Motherboard: MSI MEG X670E ACE and GIGABYTE Z790 AERO

Storage: Corsair MP600 1TB

CPU Performance Benchmarks:

We see a slight dip in performance going into CINEBENCH R23, and this is because the 3D stacked die doesn’t boost to the same frequency as that on the 7950X. We will see this slight drop in other benchmarks too, but as we can see here single core performance is slightly better.

In Blender we see a slight drop compared to the 7950X, but still neck to neck with the 13900K.

In Handbrake the CPU still holds its own, and the way we test with Handbrake prefers frequency, so the 7950X is still at the top.

AMD doing well here as well, Intel can’t seem to keep up.

Still neck and neck between the 7950X3D and the 7950X.

Not much to say here, this is still a Zen4 CPU, so memory bandwidth isn’t too crazy.

Latency is a bit higher; AMD has stated that on the 5800X3D, the 3D V-Cache adds 4 cycles of latency.

Considering the latency numbers in AIDA64, we saw this coming.

The CPU might not be as hardcore frequency heavy like the 7950X, but it still packs a big punch and in some cases, like Science Mark, Intel doesn’t fair that well.

Synthetic 3D Benchmarks:

We were actually going to leave this benchmark out since we added a bunch more, but after running it,we thought we would share the results. The reason being it shows AMD starting to take back its crown jewels from Intel. when it comes to some benchmarks.

Here is something we saw with the CPU Performance Benchmarks. When frequency is the key indicator over IPC, the 7950X does better. We see this in the synthetic benchmarks below as well, but not in actual games.

3DMark Cloud Gate, still head to head with Intel.

In FireStrike it still is overcoming Intel’s 13900K.

CPU Gaming Benchmarks:

In actual game play we see the 7950X3D overcome the results from the synthetic benchmarks, which we expected.

Far Cary 5 has the most revealing benchmark results. The IPC lift from the addition L3D cache is very strong, and we can plainly see it here.

Intel is very strong in Ashes of the Singularity: Escalation, which is funny because AMD pushed this game very hard when it launched, and now the 7950X3D shows us that AMD is still up to taking back its crown.

One thing we should remember is that AMD is using a single 8 core CCX here, up against many more active cores in the other CPUs.

Here we see it clearly beating out the 7950X.

Conclusion:

The AMD Ryzen 9 7950X3D is a very interesting CPU. It offers much better thermal and power consumption numbers than the 7950X (120W vs. 170W), and that is by design. The 3D V-Cache is a sensitive piece of technology and has hard voltage limits on the CCX it is connected to as the RVDD (ungated) and VDDM (gated L2/L3 SRAM) power rails are shared between the two through power TSVs. Those power rails supply 512x 128KB data macros and 1088x 6KB tag/LRU macros to produce a nice hefty 64MB of L3D cache, which makes this CPU one of the best gaming CPUs on the market. However, that being said, that voltage limit does mean the one CCX can’t run as fast as the other, which will result in a slight hit in productivity scenarios compared to the 7950X. The IPC is betters by a lot, and games love that, but frequency is lower.

The same reason AMD has limited overclocking to their heuristic algorithms like Performance Boost Overdrive and Core Optimizer is the same reason the 7950X performs better in productivity and the same reason the 7950X3D does really excellent in games; the extra SRAM. We know some of you were expecting the 7950X3D to dominate pretty much everything the 7950X does, but it’s a CPU running a single CCX in games and beating out dual CCX CPUs, and that is wickedly impressive. The Intel 13900K Raptor Lake has a new competitor in town, and considering both are marketed as top of the line gaming CPUs, we have to say AMD did great with the 7950X3D. The 7950X3D offers up the best of high core count productivity along with excellent, and we mean excellent, gaming performance. The 7950X3D is AMD’s answer to Intel’s Raptor Lake, and we highly recommend it.

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