Interesting article in Toms Hardware Guide: How to Speed up Your RAM - How to Tweak Your RAM in BIOS.
Search under MB/RAM for RAM.
I did not change CAS Latency nor Memory Clock.
I decreased RAS Precharge Time, RAS to CAS Delay, and Row Active Time per the tweak recommendation to MB allowable settings.
I also enabled System Accel Mode.
System runs well with new settings.