The Default SPD is indeed DDR3-1333 with 1090T, and even with Zambezi FX-series the default is the highest JEDEC up to DDR3-1866 and XMP is not a JEDEC standard it's Intel's version of 'SPD'.
Problem, in order to set the RAM Frequency >DDR3-1333 even on the 6-core AM3 you'll need to both manually set DRAM Frequency AND the FSB 240MHz (OC) or CPU-NB Frequency to 2400MHz or use ASUS's DOCP.
RAM DDR3-1866 9-10-9-27-2T @ 1.50v
AI Overclock Tuner -> DOCP
Memory Frequency -> DDR3-1866MHz ; this speed 'should' be available if not then FSB is required**
DRAM Timing Control /Enter
DRAM CAS -> 9
DRAM RAS -> 10
DRAM RAS PRE -> 9
DRAM RAS ACT -> 27
DRAM Command Rate -> 2T
Save & Exit = Yes
Now since the kit is 1.50v the DRAM Voltage and CPU-NB Voltage are 'typically' not required. ** IF DDR3-1866MHz is not available in the menu then I'll post the alternative method of FSB (OC).
DOCP by itself won't (shouldn't) cause a problem. At some point if you decide to OC the CPU then the idea is essentially the same, but AI Overclock Tuner -> Manual, OC Tuner, CPU Ratio, CPU Voltage, DRAM Frequency, etc.
IMO I would save the Profile you have now; see page 3-27 of the manual.
To 'reset' the best place to start is 'Load Optimized Defaults'; see page 3-28. Worst case if things get to the point of 'Post Failure' use the Clear CMOS procedure; see page 2-16.