As you probably already know, modern processors are no longer literally made up of a single chip, but consist of a series of interconnected subsystems, like this one itself. CPU with the cache or controller by heart. This method of interconnection, when talking about AMD processors, is called Infinity Fabric and has his own watch which dictates its operational performance.
What is Infinity Fabric on AMD processors?
Let’s start at the beginning to put things in context, so let’s first define what Infinity Fabric is. Also known by its acronym IF, we are faced with a whole system interconnect architecture patented by AMD (that means we can’t see it at Intel, for example) which is responsible for data transmission and control through the components that it has linked, which, as we put earlier as an example, can be for example the cache or the memory controller.
This connection architecture has been used in all modern AMD microarchitectures since 2017 and not just in processors, as it is also used in GPUs. In essence, Infinity Fabric is the “technology” (although it is actually an entire architecture) for interconnecting the internal components of an AMD processor, including the iGPU if you have one, the memory controller, cache, USB controller and even the network card. If you want to know how Infinity Fabric works, we have an article dedicated to it.
What is the Fabric Infinity Clock or FCLK?
As we explained, Infinity Fabric is really just a communication bus which, as such, is controlled by a clock speed that dictates its operation, and that is precisely the Infinity Fabric Clock. or FCLK. In processors Zen and Zen +, the FCLK could not be configured independently but was associated with the speed of the RAM memory, so there were big differences in performance when higher frequency RAMs were chosen.
For example, a first generation AMD Ryzen processor required RAM modules with a speed of at least 3200 MHz so as not to significantly affect the performance of the Infinity Fabric.
However, since the introduction of AMD’s Zen 2 architecture processors this has changed and now the FCLK has been decoupled from memory and can be controlled independently (at least on X570 chipset motherboards) from the BIOS. system, by being able to adjust its speed so that the system does not suffer such a performance penalty when the RAM memory is too slow.
Currently, in the Ryzen 5000 processors of the Zen 3 architecture, the FCLK is limited to a maximum of 2000 MHz, which would correspond to the operation of 4000 MHz in RAM (remember that RAM is DDR, Dual Data Rate) .
Operating modes
Keep in mind that in AMD Ryzen processors, in addition to the normal clock frequency, we have three more: Infinity Fabric Clock (FCLK) which we have already talked about, UCLK (memory controller speed) and MCLK (speed of the RAM itself). Infinity Fabric determines the speed at which processor cores can communicate with each other when they are on a different chip or with the I / O section of the processor itself.
By default, these three frequencies have a ratio of 1: 1: 1, or in other words, all three work in sync, so the FCLK will also be tied to the frequency of the RAM, but as we said before , now we have the possibility to modify this rule.
Starting with AMD Ryzen 3000 processors, using 3733 MHz or higher RAM will cause the FCLK to reduce its speed, i.e. the ratio we talked about before goes to 2: 1 by compared to the MCLK. Thus, if we install 3733 MHz of RAM, its frequency will be 1866 MHz and the FCLK will become 933 MHz.
Explained in other words, this means that the higher the speed of the RAM, the lower the performance of the Infinity Fabric, at least hit a certain limit (the 3733 MHz we mentioned earlier).
Is it worth increasing your running speed?
As we explained previously, the FCLK can now be changed directly from the BIOS in PCs compatible with the AMD processor, so if we install very fast RAMs, we might be interested in increasing its operating frequency to have more better performance … or not? The answer is yes, but with a few buts, because increasing the speed of the FCLK has certain costs.
To begin with, we are faced with the limitations that we can find when increasing this operating frequency, because it is not a parameter that changes too much. In essence, it’s worth increasing its operating speed when using 3000 or 3200 MHz of RAM, but doing so will cause RAM latencies to be out of sync and can lead to issues in the form of blue screens. in addition to the increased latencies of RAM. .
In theory and according to the famous overclocker Buildzoid, an improvement of the FCLK of at least 166 MHz compared to the value 1: 1 is “profitable” despite the fact that the latencies of the RAM memory increase. What we recommend is that if you want to “manipulate” this setting, look for the option that works best for you.
How to Change the Infinity Cloth Clock on Your PC
Changing this setting is possible on motherboards with an AMD X570 chipset, and it’s as easy as going into the BIOS and, in the Overclocking or Advanced Options section (this changes depending on the manufacturer), looking for the FCLK Frequency parameter.
Of course, if you notice any instability issues, we recommend that you lower the FCLK or reset it to its default values. A good way to check if your system is stable and if it is worth increasing this value is to take the Aida64 onboard memory performance test before and after making the change.
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