AMD Ryzen 9 7900 processor review

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Ryzen processor family

The ZEN4 CPU  

Zen 4 CPU core-based products will power Ryzen 7000 desktop CPUs (codenamed "Raphael"), high-end mobile processors (codenamed "Dragon Range"), thin & light mobile processors (codenamed "Phoenix"), and Epyc 7004 server processors (codenamed "Genoa" and "Bergamo"). A lot has been said and spoken about ZEN4; AMD single and multi-threaded performance has been excellent overall, but with competition from Intel heating up, they have a new design with lots more cache and turbo frequencies moving upwards to 5.5 GHz. Overall, Intel was king in High turbo clock frequencies but a notch weaker in IPC. On the other hand, AMD has been very strong on IPC but less so in absolute peak clock frequencies.

 

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That gave intel an advantage in many games with enthusiast performance graphics cards. In the past, a solution to bypass any performance degradation in gaming is to eliminate inter-core and inter-CCX latencies. Initially, ZEN2 addressed that to some extent, with a few efficiency solutions found at cache levels. However, getting rid of the inter-core complex partition latencies is another thing. Zen 4 will continue to use an MCM (multi-chip module), or chiplet design; it will use up to two 8-core CCDs and one I/O die. There will only be one CCX per CCD, and this CCX will consist of eight cores. The Zen 4 core's key architectural advancements include higher data TLBs for the L1 and L2 caches and a doubling of the size of L2 cache per core, from 512KB to 1MB. A translation look-aside buffer (TLB) is a memory cache that stores the most recent virtual memory to physical memory translations. It is used to speed up access to a user's memory location. 


 

AMD Ryzen 7000 Raphael Desktop CPU Specs as of January 2023:

 

ProcessorArchitectureFabrication nodeCores/ThreadsBase frequencyBoost FrequencyCacheTDPPRICES
Ryzen 9 7950X Zen 4 5nm 16/32 4.5 GHz 5.7 GHz 80 MB (64+16) 170W $699 US
Ryzen 9 7900X Zen 4 5nm 12/24 4.7 GHz 5.6 GHz 76 MB (64+12) 170W $549 US
Ryzen 9 7900 Zen 4 5nm 12/24 3.7 GHz 5.4 GHz 76 MB (64+12) 65W $429 US
Ryzen 7 7700X Zen 4 5nm 8/16 4.5 GHz 5.4 GHz 40 MB (32+8) 105W $399 US
Ryzen 7 7700 Zen 4 5nm 8/16 3.8 GHz 5.3 GHz 40 MB (32+8) 65W $329 US
Ryzen 5 7600X Zen 4 5nm 6/12 4.7 GHz 5.3 GHz 38 MB (32+6) 105W $299 US
Ryzen 5 7600 Zen 4 5nm 6/12 3.8 GHz 5.1 GHz 38 MB (32+6) 65W $229 US

So, factors like IPC, Clock frequency, and increased cache sizes will most likely result in performance improvements. In addition, AMD is bringing AVX512 instructions to Zen 4. As a result, applications that exploit this will obtain significantly bigger speed benefits.

Key changes from Zen 3

  • AVX-512 instructions support
  • L1 and L2 DTLB size increased from 64 to 72 and 2,048 to 3,072 entries
  • L2 cache doubled from 512 KiB to 1 MiB per core
  • Improved cache load, write and prefetch from/to register (less latency).
  • Higher Transistor Density, due to 5nm process
  • Capable of higher all-core clockspeeds (shown by AMD to reach 5GHz+ on all cores)
  • An igpu in every processor
  • PCIe Gen 5.0
  • DDR5

There is a total of 64MB of L3 cache (ZEN3 32 MB and ZEN2 had 16MB per CCX ) shared across the cores in the CCX. There's also 1MB of L2 cache per core within the CCX, for 8MB of L2 cache per CCD.  Like its predecessor, Zen 4 includes up to two Core Complex Dies (CCDs) manufactured using TSMC's 5nm technology and one I/O die manufactured with 6nm. Previously, the I/O die on Zen 3 was manufactured using GlobalFoundries' 14nm technology. For the first time in any Zen architecture, the I/O die of Zen 4 incorporates RDNA 2 graphics. Zen 4 is the first desktop CPU to utilize the 5nm manufacturing technology. On Zen 4, the L2 cache increased from 512KB to 1MB per core.


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Integrated graphics

In the past AMD offers CPU and APU's, APUs are a processor with integrated graphics. AMD is seemingly changing this approach as all Raphael Zen4-based processors will be fitted with an RDNA2 graphics unit, which is good news. Those who don't play games or need a separate video card for some other reason needed to purchase a (hopefully) inexpensive card in addition to a standard Ryzen processor or even connect a monitor. This disadvantage grew much more severe due to the scarcity of graphics cards. Every Ryzen 7000 series CPU includes an integrated graphics processing unit, and that IGP resides in the I/O chip (6nm). Even though it is based on the contemporary RDNA2 architecture, it will likely have just two compute units. Therefore, it will not be suited for playing modern games.


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Overall, AMD intended to use the smaller 6nm node size to incorporate a nice quality-of-life boost with the addition of graphics capabilities.

Architectural Basics

  • 2x RDNA 2 compute units 
  • 4x ACE 
  • 1x HWS 
  • Encode: H.265 10bpc/8bpc, H.264 10bpc/8bpc 
  • Decode: AV1 10bpc/8bpc, VP9 10bpc/8bpc, H.265 10bpc/8bpc, H.264 10bpc/8bpc
  • Display:
    • HDMI 2.1 with: HFR, 48Gbps FRL, DSC, HDR10+, and VRR extensions
    • DisplayPort 2.0 Ready with: Adaptive-Sync, DSC, UHBR10, and HDR extensions

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