CPU-Z – DDR4 with an AMD Ryzen 7 3700X/Intel Core i9 9900K, with XMP enabled

X to the MP yo!

Let’s start with CPU-Z. It’s the basic tool for checking the current configuration of the system. In most cases, you should just enable the XMP profile, and that’s it. Otherwise, at default settings, the memory will be running at 2133 MHz, and that can slow down your rig. Sometimes XMP won’t work, so you might have to set the timings manually. With the Asus Strix Z390-E Gaming, all it took was to change one setting (XMP profile with DDR4-4000), save the BIOS, and reboot. For Aorus X470 Gaming 7 WIFI  we didn't use the XMP.  

We haven’t encountered any problems when booting the Intel system, and it started with the memory running at 4000 MHz without any issues. With AMD, it wasn’t so straightforward, as the Infinity Fabric divider can’t stay 1:1 for this kind of frequency. Running at 4000 MHz would cause quite severe performance decrease that's why we have settled at 3600 MHz with tighter timings.

One remark though: There's QVL available on the manufacturer’s website. We haven’t encountered any problems, and the system booted with the memory running at 4000 MHz without any issues on the Intel system. Basic info about the used CPUs and motherboards. AMD first:

Then the Intel system.

 Now what we have here for AMD:

And for Intel:

DDR4 does indicate a double data rate, so you don’t have to worry about the displayed memory clock, as the effective RAM frequency is 3600 MHZ. For X470/X570 or Z370/Z390, there’s no problem with achieving even higher frequency clocks with suitable RAM.

Please make a note of this: In Ryzen 3000 systems, as soon as you go higher than DDR4-3733, a 2:1 multiplier kicks in, and Infinity Fabric starts working at half the memory clock frequency (you can force a 1:1 setting, although this might make your system less stable). So, for the best overall system performance/stability, we recommend stopping at DDR4-3600.