Memory overclocking:
Once again, we will start our tests with the memory. The idea is to be able to use the best profile in combination with the processor overclocking.
Well, let’s start with a theoretical reminder since there are changes with the arrival of the ZEN 4 architecture as far as memory is concerned. While for the Ryzen 5000, the standard was to keep a 1:1:1 ratio between mclk:uclk:fclk, this will change with the Ryzen 7000. Indeed, they adopt the DDR5 memory. This one sees its frequency increasing, which implies changes in these ratios. AMD now recommends for AM5 motherboards in DDR5 a 1:1 ratio for the mclk:uclk and to finally leave the fclk in AUTO which will automatically set it to 2000 MHz. Theoretically, this is how it will behave:
- DDR5-4800 will give with the new ratios 2400:2400:2000 MHz (mclk:uclk:fclk)
- DDR5-5200 will give with the new ratios 2600:2600:2000 MHz (mclk:uclk:fclk)
- DDR5-6000 will give with the new ratios 3000:3000:2000 MHz (mclk:uclk:fclk)
Well, it may seem a bit complicated like that, but we’ll explain it all to you. First of all, don’t panic, if you activate your XMP or EXPO profile in the BIOS, everything will be set up automatically. The explanations we give you here are for those who want to overclock their memory kit.
fclk, mclk, uclk, a little reminder:
The fclk is the frequency of theInfiny Fabric which can be, since the previous generation, controlled independently via the BIOS parameters. By default, this value is set to AUTO mode and it is the motherboard that will manage its frequency to ensure the stability of the system. Its maximum frequency is around 2100/2200 MHz but it also depends on the quality of your processor, but that’s the lottery that will decide. The mclk also sometimes called “memclk” is the frequency of your memory kit and the uclk is the frequency of the memory controller.
You should also know that if you exceed the frequency of 6000 MT/s with your memory kit, automatically the frequency of the memory controller (uclk) will switch to a ratio of 1:2 always in order to ensure system stability. AMD indicates that the best performing frequency and ratios are 3000:3000:2000 (mclk:uclk:fclk).
Memory overclocking via BIOS profiles:
This ROG Crosshair X670E Extreme has several memory profiles within the BIOS depending on the type of chips in your memory kit. Here we know that on our GSKill kit, these are Hynix chips. These are the same profiles that were available in the BIOS of the Crosshair X670E Gene. The two BIOS are almost carbon copies.
So there are two profiles that we can test. The first one goes through very easily and the second one needs, with our memory kit, a little more voltage than what is expected. We had to increase the VDDQ voltage from 1.45 v to 1.5 v. Here are the benchmarks of these two profiles under Geekbench 3.4.4.
And finally, above, the table of the performance gain obtained with these two profiles available in the BIOS.
As you can see, in the end, the two profiles offer almost the same performance. As you know, it is the memory overclocking that is the most delicate and we will see in the next few weeks how to improve on this point.
