How We Tested
Gigabyte’s X99 SOC Champion and MSI’s X99S XPower AC are the two boards Geil certifies for DDR4-3400 via XMP, yet these are not the boards we found most conducive to memory testing. That’s mostly due to their number of available ratios, though. We wanted to see what would happen if we installed these into the same board used in our standard DDR4 memory testing configuration.
Photoshop allowed me to combine several screenshots into a single image and focus only on the automatic configuration settings. Asus’ X99-Pro appears to have thrown its hands up in surrender and configured all kinds of weirdness, beginning with a 167MHz “CPU Strap” (a core-side to I/O-side base clock ratio of 5:3) with a 170MHz BCLK and 22x CPU multiplier. CPU core voltage is bumped to 1.20V and DRAM to 1.35V, which results in an actual DRAM voltage of 1.37 to 1.38 volts. The first problem with those settings is that two of our Haswell-E CPUs start to lose stability with a 1.37V DRAM signal, and we haven’t found a memory controller voltage suitable to fix that issue.
No boot there, but what about the MSI X99S XPower AC?
A little cropping and cramming allows us to see in one image that the MSI motherboard, when XMP-3400 is enabled, sets the board to 127.6MHz BCLK, with a hidden 5:4 core-to-I/O strap ratio and hidden 30x CPU multiplier. The 1.35-volt DRAM setting measures 1.37 to 1.38 volts, and manually dropping the DIMM voltage down to 1.330 to compensate for MSI’s over-voltage makes the memory unbootable.