What you need to know about AMD’s Ryzen 7000 series Zen 4 processors
How did AMD achieve their Zen 4 performance gains?Â
With Zen 4, AMD has delivered impressive single-threaded performance gains over their Zen 3 based processors. These performance gains come from two main areas, frequency boosts and IPC increases.Â
As mentioned on the previous page, IPC means Instructions Per Clock, and higher levels of IPC simply means that a processor can do more work per clock cycle. IPC increases come from architectural changes, be it changes to core layouts reductions in internal latencies, better branch predication or improvements to various areas of a CPU’s core design.Â
With Zen 4, AMD has refined their Zen 3 core design and have made significant changes to their front-end and branch predictor. Additionally, AMD has tweaked their core design to enable higher core frequencies, allowing Zen 4 to deliver more performance per clock cycle and more clock cycles over a given time period. These performance gains are complimentary, and have resulted in AMD’s huge single-threaded performance gains with Zen 4.Â
IPC – Don’t expect a 13% performance gain everywhere
While enthusiasts and companies like to give specific IPC improvement numbers, the simple fact is that IPC increases can vary wildly on a test-by-test basis. AMD’s 13% IPC increase number comes from an average of multiple workloads that include both gaming and productivity focused applications and benchmarks.Â
Simply put, Zen 4 users should not expect a 13% increase in IPC over Zen 3 CPUs across all workloads. Some workloads will see lower performance increases and others will see larger performance increase. That said, an average IPC gain of 13% is high, and AMD’s huge number of design tweaks with Zen 4 should enable performance gains within almost all workloads. Beyond that, workloads that do not benefit from Zen 4’s design tweaks should benefit from Zen 4’s increased clock speeds.
Below, we can see that Zen 4 CPUs can deliver between 1% and 39% performance improvements over their Zen 3 counterparts when running at the same 4GHz fixed clock speeds. In some cases, Zen 4 can deliver staggering IPC gains, while in others Zen 4 only delivers minor performance improvements. Even so, Zen 4’s clock speed changes alone will enable increase performance levels over Zen 3 in practically all workloads.
How did AMD deliver more IPC?Â
AMD’s IPC increases with Zen 54 come from five main areas; Zen 4’s front-end improvements, changes to the CPU’s Load/Store mechanisms, AMD’s more accurate branch predictor, their new execution engine, and the Ryzen 7000 series’ enlarged L2 cache.Â
With Zen 4, AMD has improved their core IPC by changing a lot of areas of their core architecture. This allows AMD’s IPC gains to apply to a wide range of applications, enabling performance gains across most applications. With Zen 4, AMD’s focus was mostly on their front-end, an are where AMD saw the most need for improvement over Zen 3.
AVX-512Â
A new addition for AMD is support for AVX-512, which can be used to accelerate AI and various HPC workloads. For desktop PC users, AVX-512 can be very useful for emulators like RPCS3, and can significantly accelerate other niche workloads.Â
With Zen 4 supporting AVX-512, AMD has gained support for a feature that Intel has basically abandoned with Alder Lake. Alder Lake lacks official support for AVX-512, gifting AMD with a selling point that was once one of Intel’s strong points.Â
AMD has stated that they have enabled AVX-512 support without creating a situation where clock speeds will vary wildly when AVX-512 is enabled. This should mean that AVX-512 should not cause clock speeds to dramatically decrease with Zen 4, making AMD’s implementation better than the implementation found in older Intel processors (I’m looking at your Skylake-X).
Performance per Watt Improvements
Thanks to AMD’s new core architecture and their use of 5nm lithography, AMD has deliver significant increases in power efficiency with their Zen 4 Ryzen 7000 series processors. With Zen 4 AMD can deliver the same performance as Zen 3 with 62% less power or 49% more performance with the same power.Â
What this means is that AMD’s Zen 4 CPUs should be awesome when they are eventually released to mobile customers. Performance/watt is everything for the laptop market, and that should make Zen 4 Mobile a transformative product for AMD.
