AMD Ryzen 9 7900X3D in the benchmark test: are six cores the power?
AMD announced the new Ryzen 7000X3D models at CES in early January 2023. Since 28.02. the 16-core Ryzen 9 7950X3D (PCGH test) and the 12-core Ryzen 9 7900X3D are available on the market. The official start for the two Ryzen 9 processors only felt on paper. In a separate article on PCGH, we report on dealers who offer the 7950X3D and 7900X3D in the quasi-live ticker. So far there is no sign of a nationwide delivery capability. Caseking shows for that Ryzen 9 7950X around 9.3. as delivery date. At least we now know how much the 12-core 7900X3D costs in Germany. At Mindfactory you can see AMD’s announced price of 679 euros. Also at Caseking this price will be communicated. We are curious to see whether the availability will improve.
We would like to thank our partner Zed Up for providing the AMD Ryzen 9 7900X3D test sample. The CPU was sealed upon arrival, conforming to a standard box model found in stores. There hasn’t been a sample from AMD so far, but no further NDA regarding the 7900X3D either. We can therefore fire from full cylinders, which is what we are doing now.
AMD Ryzen 9 7900X3D: overview and specifications
With the 12-core 7900X3D, AMD is doing something it’s never done before. Ryzen 7 5800X3D and Ryzen 9 7950X3D can each clamp eight cores with 3D cache. However, since a 7900X(3D) only has a total of twelve cores, each distributed over one CCD, the big question before the launch was how AMD would distribute the cores in the 3D model: A combination of 8+4 or 6+ 6 were realistic. The secret was only revealed a few days ago, which we can now confirm: Ryzen 9 7900X3D relies on a combination of two times six cores. This means that “only” six cores rely on the 3D V-Cache, while the other six cores are taken over by the 7900X. This results in an interesting combination that readers and users from the PCGH community wanted back in the days of Ryzen 5000: a 3D cache CPU with six cores. We test the 7900X3D from the factory and also deliver a simulated “7600X3D”, i.e. a Zen 4 3D CPU that only uses six cores with 3D V-Cache (however, you will only be able to admire the latter in a later article ). AMD has not yet announced a “Ryzen 5 7600X3D” and it is questionable whether this CPU will ever exist. Nevertheless, we will allow ourselves a simulation in the coming days, since we were also very interested in how well a 3D CPU with only six cores works.
| Model | cores | tact | R.A.M. | IGP | L3 cache | TDP / PPT in watts | price in euro |
|---|---|---|---|---|---|---|---|
| Ryzen 9 7950X | 16c/32t | Up to 5.7GHz | DDR5-5200 | RDNA 2, 2CU | 64 MiByte | 170 / 230 | 599 |
| Ryzen 9 7950X3D | 16c/32t | Up to 5.7GHz | DDR5-5200 | RDNA 2, 2CU | 128 MiByte | 120 / 162 | 789 |
| Ryzen 9 7900X | 12c/24t | Up to 5.6GHz | DDR5-5200 | RDNA 2, 2CU | 64 MiByte | 170 / 230 | 490 |
| Ryzen 9 7900X3D | 12c/24t | Up to 5.6GHz | DDR5-5200 | RDNA 2, 2CU | 128 MiByte | 120 / 162 | 679 |
| Ryzen 9 7900 | 12c/24t | Up to 5.4GHz | DDR5-5200 | RDNA 2, 2CU | 64 MiByte | 65 / 88 | 445 |
According to AMD, a Ryzen 9 7900X3D comes with 12 cores, which can provide up to 24 threads thanks to SMT. The maximum clock is 5.6 GHz and applies to the single-core boost. The base clock is 4.4 GHz and the TDP is 120 watts. Like the big brother Ryzen 9 7950X3D, the 12-core relies on the additional 3D cache, which packs a further 64 MiByte in addition to the regular 32 MiByte L3 cache (per CCD), which gives the processor access to a total of 128 MiByte. A 7900X3D also has to make do with a lower maximum temperature of 89 °C. The connectivity is identical, the CPU comes with 24 PCI Express 5.0 lanes, support for up to 128 GiByte DDR5 memory (max. DDR5-5200) and the integrated RDNA2 graphics unit. On the other hand, if you use all DIMMs on the mainboard, the maximum speed for the main memory falls back to DDR5-3600.
Of course, a 7900X3D also relies on the asymmetrical design: The CCD with 3D cache clocks at about 5.0 GHz under load and can accelerate games with the help of the more lavish L3 cache. The other CCD behaves exactly like the 7900X: the six cores clock at up to 5.6 GHz and are used when a high clock frequency is required. AMD thus combines both advantages in one CPU. In order for the operating system to recognize whether a game or an application is currently running, AMD relies on a combination of a new chipset driver that comes with an “AMD 3D V-Cache Performance Optimizer” and the associated driver for Windows 10/11 and the current version XBOX Game Bar, which in combination with the game mode of Windows reports whether the user is in a game or not. See the Ryzen 9 7950X3D review, on page 1, below for more information.
On the next page we deal with the performance of the new 12 core. We’ve already mentioned that AMD has done a good job here, but the numbers in the benchmarks are something else. Then we deal with the efficiency and finally draw a conclusion. Are six cores enough for modern games?
Reference-www.pcgameshardware.de
