Intel’s Rocket Lake CPUs were hiding a feature similar to AMD’s Infinity Fabric Clock

Intel will official unveil its Rocket Lake-S CPUs on 16^th March, whereas the official performance review of the SKUs will be unveiled on 30^th March. And we already know that some of the retailers are already selling the Rocket Lake processors even though Intel will not make the processors available before March 30.

Though, the availability of the processors from the retailers has allowed us to get many unofficial reviews and benchmarks of the models. But, in recent posts on the Chinese Chiphell forums, Intel’s Rocket Lake CPUs now support a memory overclocking feature that is very similar to AMD’s Infinity Fabric Clock (FCLK) on the Ryzen 3000 and Ryzen 5000 CPUs.

In the previous leaked benchmarking details, this particular feature was missing, but Chiphell does justice to the feature. According to the post by Chiphell, the Rocket Lake processor which appeared is an Intel Core i7-11700K running on an MSI MEG Z490I Unify motherboard. The motherboard BIOS lets users select two “gears” for the CPU IMC (integrated memory controller).

According to sources, Gear 1 is 1:1 (synchronous mode), while Gear 2 is ½:1 (asynchronous mode). It seems that the second option is the same as the Infinity Fabric Clock (FCLK) on the Ryzen platforms that can be modified to work independently from the unified memory controller clock (UCLK) and the memory clock (MEMCLK).

Currently, the Ryzen 3000 CPUs can run the FCLK in synchronous mode (1:1 ratio) up to 1,800 MHz ( DDR4-3600), with very few “gold” samples hitting FLCK 1,900 MHz (DDR4-3800). While the Ryzen 5000 offers a little over 2,000 MHz (DDR4-4000).

In the post, Chiphell states that the 1:1 option for the Rocket Lake CPUs appears to be capped at around 1,866 MHz (DDR4-3733). It makes the CPU go toe-to-toe with the Ryzen 3000 CPUs.

To show the memory latency of the Rocket Lake CPU, the Chiphell user first tested a DDR4-4000 kit with 18-20-20-40 1T timings. The 1:1 threshold led to 61.3 nanosecond latencies in AIDA64 and with a DDR4-3600 14-14-14-34 2T kit with uncore clocks set to 4,100 MHz and got 50.2 ns latency.

MSI is going to unveil new Z590 mobo models, so it would be interesting to see how this would affect the performance of intel’s CPUs.

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