The memory modules are all being detected correctly. However it appears like tri-channel memory might be selected and for whatever reason, it deciding that its incompatible and dropped down to a single channel only (A). This could happen if channels B or C had different timings, but at least from the screenshot you provided they appear to all be exactly the same. If it were me, i would try the following 1. Reset the BIOS to fail-safe defaults (Press F6 from the screenshot) 2. Clear the CMOS using a jumper on the motherboard. 3. Reflash the latest BIOS and if you are on the latest, then reflash the current BIOS version.