interestingly I switch between 2 stable configs, one which is 9x373 odd with memory (4 banks worth) @ 1140 MHz CAS5

and another which is 9x392 with memory @ 785 CAS4

both have been stable. I have noticed occasionally in the past that the config 1 has been unstable - depending on hardware config - butI think I'vfe finally nailed it

the high freq RAM config was stable this week until I added a SSD drive - so instead of 2 HDDs - now 3 - the only thing I can think of is that when I get to a certain loading on the northbridge (ie numbers of HDDs etc) it gets to a point where it can't cope with all of those AND 4 banks of high frequency RAM. Oh well - doesn't really matter. Northbridge volts are set to 1.55V btw.