Testing and Performance Overview
During our testing the Z390 Aorus Master delivered solid performance however we noted a quirk in the clock speed of our Core i9-9900K CPU as the base clock was 102.03MHz, rather than the default 100MHz. At first we put this down to Gigabyte sneaking a couple of extra percentage points on performance, however the reality was more nuanced.
Some experimentation proved it was actually a question of XMP settings. With DDR4-3,200MHz RAM the base clock remained at 100MHz regardless of whether or not we enabled XMP. By contrast with DDR4-3,400MHz RAM the base clock rises to 102.03MHz when XMP is enabled. If we divide 3,400MHz by 102.03 we get 3,333MHz so it follows that 3,333MHz is a ‘natural’ speed for RAM in the BIOS and that selecting 3,400MHz requires a slightly higher base clock to get the RAM to operate at full speed.
We do not consider this to be a problem but would have preferred it if Gigabyte had spelled out more clearly what was going on when XMP was enabled.