Tuesday, April 18th 2023
Ryzen 7000X3D Series: A Brief Technical Chat with AMD
Earlier this month, AMD wrapped up the launch of its incredible Ryzen 7000X3D processor series, which storms the company's gaming performance competitiveness against Intel back to the top, setting it up for the crucial Spring-Summer season, when PC gamers tend to upgrade and play the latest games. The 3D Vertical Cache memory deployed on the Ryzen 9 7950X3D, 7900X3D, and Ryzen 7 7800X3D, supercharges the gaming performance of these processors, and our testing has shown that the 7800X3D is all that an elite gaming PC build needs if all you're doing is playing games with some domestic productivity on the side; whereas the 7950X3D is for those into heavy content creation and application workloads besides gaming, which means AMD levels up to Intel on both fronts.
We have extensively covered the technical aspects of what 3D Vertical Cache is, and how it works, in our reviews of the 7950X3D and 7800X3D. It is a fast 64 MB slice of SRAM cache stacked on top of the 32 MB on-die L3 cache of "Zen 4" chiplets, which extends the L3 cache size to 96 MB. This has a profound impact on gaming workloads, as the CPU cores have more amount of game data at much lower latency than DRAM. As part of our coverage of the Ryzen 7000X3D processor series, we had the opportunity to interview AMD on some of the technical aspects of Ryzen 7000X3D processor series. We also took the opportunity to ask a few general questions about the Ryzen 7000 desktop processor series itself. You can also catch our interview with Robert Hallock, the former technical marketing head, for some additional questions that you may find relevant.
TechPowerUp (TPU): Does the 7900X3D have a 6+6 core CCD configuration, or 8+4?
AMD: While the Ryzen 9 7950X3D processor has 2 CCDs, each of them with 8 cores, the Ryzen 9 7900X3D processor has 2 CCDs with 6 cores. The Ryzen 7 7800X3D processor owns 1 CCD with 8 cores.
The Ryzen 9 7900X3D processor offers two CCDs with the same L3 cache configuration as the Ryzen 9 7950X3D processor. But be aware - the core configuration differs: The CCD of the 7900X3D processor has six cores enabled, however one with the same 64 MB L3 cache added, or, 10.7 MB of L3 cache per core, as the 7950X3D processor CCD with AMD 3D V-Cache.
TPU: The 3DV Cache operates at CPU core voltage?
AMD: The new Ryzen has a CCD with stacked level 3 cache. This creates a balance between clock and cache and allows the chips to achieve maximum performance. CCD 0 has 96 MiB of L3 cache, while CCD 1 only has 32 MiB, but can clock faster.
TPU: Is the cache die the same design as the one used on 5800X3D? If not, anything you could share on what's new?
AMD: At a silicon level, the AMD 3D V-Cache technology on Ryzen 7000 X3D processor is largely the same technology as was used on Ryzen 5800X3D processors. The most significant improvements are in the firmware and product development activities, through which we have now enabled 2-CCD versions, PBO, and Curve Optimizer functionality.
TPU: Should overclockers be careful with how much voltage they apply on the X3D SKUs? (versus what's safe on the non-X3D SKUs)
AMD: The safe voltage range is the one programmed from the factory, which is automatically controlled by the firmware underlying the power management and boost algorithms. PBO, and Curve Optimizer functionality are enabled, for this generation. Users can fine tune via the BIOS or use Ryzen Master.
TPU: Is the IGP able to access the 3DV Cache?
AMD: AMD Ryzen 7000 CPUs have the same basic graphics engine with 2 AMD RDNA 2 CU's. The built-in graphics is meant to provide basic display-out capabilities for troubleshooting, as well as enough performance for watching videos and doing basic office tasks. The built-in graphics resides on the I/O die and is a self-contained unit with its own L2 cache. It does not access the L3 cache on any of the compute dies.
Can we expect BIOS-level scheduler toggles such as "prefer cache," and "prefer frequency" to be incorporated to Ryzen Master? Able to they apply on-the-fly without restart?
AMD: Currently, as you may know, the CCD/Thread optimizing for AMD 3D V-Cache is done via the OS and Microsoft's Xbox Game Bar, when gaming. We can see if there is a desire to be able to manually toggle the CCD, besides disabling one via Ryzen Master or in the BIOS.
TPU: Can you please detail the technical reason behind lowering the Tjmax value to 89 Celsius, down from 95C?
AMD: The AMD 3D V-Cache DIE requires certain power and voltage. We determined the max. CPU core voltage for safe operation to be slightly lower for Ryzen processors with AMD 3D V-Cache, as those voltages are tied. As a result you see our Ryzen 7000 Series processors with AMD 3D V-Cache have an official TDP of 120 W, instead of 170 W for some of the non-3D V-Cache versions. This is by design and also means we could run a lower TjMax.
With that reduced TDP we do see many of the 3rd party coolers that are confirmed to be compatible and working well with AMD Ryzen 7000 Series processors, to be work great on Ryzen 7000 processors with AMD 3D V-Cache.
TPU: What happens if I run a game in the foreground and a renderer in the background? What if I alt+tab and switch away from the game?
AMD: The AMD 3D V-Cache CCD is utilized for any 3D application that is running. Any other workloads are scheduled to be executed by the second CCD (should the CPU in question feature two CCDs). When performing a combination of these workloads, both CCDs will be utilized accordingly.
TPU: How does the PPM Driver detect a game? Just based on MS Game Bar detection?
AMD: Essentially when a Ryzen 7000X3D processor goes into "game mode", it's because Xbox game bar detects a game is running and puts the workload on the CCD with the AMD 3DV-cache technology.
TPU: The 7800X3D will run at optimum performance without any Performance Optimizer Driver / PPM Driver / Game Bar?
AMD: We always recommend to follow our teams instructions when testing AMD Processors. This includes installing the correct AMD Chipset Software as well as ensuring you are running on an optimized OS, for testing AMD 3D V-Cache technology. With a single CCD product with AMD 3D V-Cache technology you will find that a workload capable of benefiting from higher levels of L3 cache, will automatically see optimized performance, when the basic steps are followed.
TPU: In our testing, we noticed some outliers to the 3DV cache optimization. Is AMD identifying and optimizing for these games? Will we see AMD Chipset Software receive more frequent updates for game optimizations going forward?
AMD: While some games highly benefit from having more L3 cache, other may see less of a performance jump. Similar to when AMD first introduced Ryzen and Threadripper CPUs, with Chiplet design, and as we introduced the Ryzen 7 5800X3D processor, we are partnering closely with Microsoft to help optimize the built in thread scheduler in Windows for AMD Ryzen & Threadripper processors to ensure full benefit from our technologies. Additionally, we continue to work closely with Game Developers to ensure game threads are optimally scheduled to take advantage of the large AMD 3D V-Cache technology available on Ryzen 7000X3D processors.
Catch the TechPowerUp Reviews of the Ryzen 9 7950X3D | Ryzen 7 7800X3D | Ryzen 9 7950X3D with non-X3D CCD Disabled
We have extensively covered the technical aspects of what 3D Vertical Cache is, and how it works, in our reviews of the 7950X3D and 7800X3D. It is a fast 64 MB slice of SRAM cache stacked on top of the 32 MB on-die L3 cache of "Zen 4" chiplets, which extends the L3 cache size to 96 MB. This has a profound impact on gaming workloads, as the CPU cores have more amount of game data at much lower latency than DRAM. As part of our coverage of the Ryzen 7000X3D processor series, we had the opportunity to interview AMD on some of the technical aspects of Ryzen 7000X3D processor series. We also took the opportunity to ask a few general questions about the Ryzen 7000 desktop processor series itself. You can also catch our interview with Robert Hallock, the former technical marketing head, for some additional questions that you may find relevant.
AMD: While the Ryzen 9 7950X3D processor has 2 CCDs, each of them with 8 cores, the Ryzen 9 7900X3D processor has 2 CCDs with 6 cores. The Ryzen 7 7800X3D processor owns 1 CCD with 8 cores.
The Ryzen 9 7900X3D processor offers two CCDs with the same L3 cache configuration as the Ryzen 9 7950X3D processor. But be aware - the core configuration differs: The CCD of the 7900X3D processor has six cores enabled, however one with the same 64 MB L3 cache added, or, 10.7 MB of L3 cache per core, as the 7950X3D processor CCD with AMD 3D V-Cache.
TPU: The 3DV Cache operates at CPU core voltage?
AMD: The new Ryzen has a CCD with stacked level 3 cache. This creates a balance between clock and cache and allows the chips to achieve maximum performance. CCD 0 has 96 MiB of L3 cache, while CCD 1 only has 32 MiB, but can clock faster.
TPU: Is the cache die the same design as the one used on 5800X3D? If not, anything you could share on what's new?
AMD: At a silicon level, the AMD 3D V-Cache technology on Ryzen 7000 X3D processor is largely the same technology as was used on Ryzen 5800X3D processors. The most significant improvements are in the firmware and product development activities, through which we have now enabled 2-CCD versions, PBO, and Curve Optimizer functionality.
TPU: Should overclockers be careful with how much voltage they apply on the X3D SKUs? (versus what's safe on the non-X3D SKUs)
AMD: The safe voltage range is the one programmed from the factory, which is automatically controlled by the firmware underlying the power management and boost algorithms. PBO, and Curve Optimizer functionality are enabled, for this generation. Users can fine tune via the BIOS or use Ryzen Master.
TPU: Is the IGP able to access the 3DV Cache?
AMD: AMD Ryzen 7000 CPUs have the same basic graphics engine with 2 AMD RDNA 2 CU's. The built-in graphics is meant to provide basic display-out capabilities for troubleshooting, as well as enough performance for watching videos and doing basic office tasks. The built-in graphics resides on the I/O die and is a self-contained unit with its own L2 cache. It does not access the L3 cache on any of the compute dies.
Can we expect BIOS-level scheduler toggles such as "prefer cache," and "prefer frequency" to be incorporated to Ryzen Master? Able to they apply on-the-fly without restart?
AMD: Currently, as you may know, the CCD/Thread optimizing for AMD 3D V-Cache is done via the OS and Microsoft's Xbox Game Bar, when gaming. We can see if there is a desire to be able to manually toggle the CCD, besides disabling one via Ryzen Master or in the BIOS.
TPU: Can you please detail the technical reason behind lowering the Tjmax value to 89 Celsius, down from 95C?
AMD: The AMD 3D V-Cache DIE requires certain power and voltage. We determined the max. CPU core voltage for safe operation to be slightly lower for Ryzen processors with AMD 3D V-Cache, as those voltages are tied. As a result you see our Ryzen 7000 Series processors with AMD 3D V-Cache have an official TDP of 120 W, instead of 170 W for some of the non-3D V-Cache versions. This is by design and also means we could run a lower TjMax.
With that reduced TDP we do see many of the 3rd party coolers that are confirmed to be compatible and working well with AMD Ryzen 7000 Series processors, to be work great on Ryzen 7000 processors with AMD 3D V-Cache.
TPU: What happens if I run a game in the foreground and a renderer in the background? What if I alt+tab and switch away from the game?
AMD: The AMD 3D V-Cache CCD is utilized for any 3D application that is running. Any other workloads are scheduled to be executed by the second CCD (should the CPU in question feature two CCDs). When performing a combination of these workloads, both CCDs will be utilized accordingly.
TPU: How does the PPM Driver detect a game? Just based on MS Game Bar detection?
AMD: Essentially when a Ryzen 7000X3D processor goes into "game mode", it's because Xbox game bar detects a game is running and puts the workload on the CCD with the AMD 3DV-cache technology.
TPU: The 7800X3D will run at optimum performance without any Performance Optimizer Driver / PPM Driver / Game Bar?
AMD: We always recommend to follow our teams instructions when testing AMD Processors. This includes installing the correct AMD Chipset Software as well as ensuring you are running on an optimized OS, for testing AMD 3D V-Cache technology. With a single CCD product with AMD 3D V-Cache technology you will find that a workload capable of benefiting from higher levels of L3 cache, will automatically see optimized performance, when the basic steps are followed.
TPU: In our testing, we noticed some outliers to the 3DV cache optimization. Is AMD identifying and optimizing for these games? Will we see AMD Chipset Software receive more frequent updates for game optimizations going forward?
AMD: While some games highly benefit from having more L3 cache, other may see less of a performance jump. Similar to when AMD first introduced Ryzen and Threadripper CPUs, with Chiplet design, and as we introduced the Ryzen 7 5800X3D processor, we are partnering closely with Microsoft to help optimize the built in thread scheduler in Windows for AMD Ryzen & Threadripper processors to ensure full benefit from our technologies. Additionally, we continue to work closely with Game Developers to ensure game threads are optimally scheduled to take advantage of the large AMD 3D V-Cache technology available on Ryzen 7000X3D processors.
Catch the TechPowerUp Reviews of the Ryzen 9 7950X3D | Ryzen 7 7800X3D | Ryzen 9 7950X3D with non-X3D CCD Disabled
29 Comments on Ryzen 7000X3D Series: A Brief Technical Chat with AMD
The 7900X3D can feel faster since AMD turned down the 7800X3D's average boostfrequency to make the more expensive CPUs more attractive...
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If you think about efficiency Zen3 runs best around 4,2-4,4Ghz. I have a 5800X3D running 4,42Ghz on all cores. ONE cores uses ~4W power, if HWiNFO is right. ~39W total.
On a 5950X, which I also owned, one core boosted stock with 1.5V to 5.05Ghz and during Cinebench it consumed ~16W of power, according to HWiNFO. ~80W total.
Of course there are some other things inside the CPU that use power, like the IO-die and so on. Measuring one core alone is hard....
As another comparision, my 5800X3D uses 105W power for 4,42Ghz on all cores during Cinebench. The 5950X used 80W for 1-2 Cores on 5,05Ghz. When using all 16 cores it's clocks went down to 3,8Ghz with 142W of power. With a bit of tuning I got it to 4,2Ghz with 142W as well.
With the 5950X tuned down from 5,05Ghz to 4,2Ghz the powerusage from 1-2 core use like in cinebench-single, went down by almost 50%!!! and I lost only 10% points in CB. Imagine that...
The 7000X3Ds run closer so that best efficiency curve then other 7000X CPUs, similar to the example I gave.
Now the problem: Most people want the most amount of performance out of their CPUs, ignoring efficiency. I do not. I don't want a 1kW heater in my room, but I also want a 4k gaming experience as best as possible.
It gets harder to archieve that, If AMD completely locks down the CPU. Yadda yadda 3D-Cache gets damaged... You can lock out CPU overclocking, but still enable undervoltaging...