Overclocked settings for G.SKILL TRIDENT X DDR3-2400 PC3-19200 4096MBx4

[maxskill]

Using ASRock FM2A88X Extreme6+ and was using two DDR3-2400 memory modules only with choosing the XMP setting. Everything worked well with two modules, but to add two more modules, the BIOS force detection as DDR3-1600. I managed to detect stably DDR3-2133 changing "CPU Frequency Multiplier BN" from x18.0 1800 Mhz to x19.0 1900 Mhz.

The memories work correctly regardless of slot used. It is not a problem of the memories, or the motherboard.
The problem is that not know Overclocked settings for the memories. I tried setting "CPU Frequency Multiplier BN" to x19.0 1900 Mhz and memories are stable for DDR3-2133 XMP setting.
I've adjusted since x20.0 to up x24.0 for a DDR3-2400 XMP setting, but is unstable.

All changes are made with DRAM Timing Configuration to auto.

What Overclocked settings, I have to use to use DDR3-2400 x4?

[GSKILL TECH]

Manually input DRAM frequency, timings, and Voltage. XMP may not be good because it is designed for a single kit of RAM. Make sure each kit is installed in the same color slots. For 4 modules, you will need to increase CPU-NB Voltage. Try +0.15V to see if the system can be stable.