yep, i found slot 1 and 2 more stable.

i don't get blue screens or re starts, BUT i still can't pass prime 95, or 3dmark2001. sideeffect, you have nearly the same rig as me, this is my ram
http://www.gskill.com/f1-4000usu2-2gbhz.htm

and at the bottom is a pic of the ram and A64 tweeker running with the right settings ......
would the 180nfm bios help me ... or should i go for TCCD edition that you've done ?
thing is. i know alittle about CA,RAS etc ... but NO WAY enough to understand a64 tweeker !
could some one please help me, as i want to know weather to RMA my ram or not.