I have a similar issue too.
Same mobo (nf4-d converted to sli) i'm assuming, and I used 2x ocz platinum rev. 2's tccd, so I ordered another pair, but I'm positive one stick has gone bad. Even when set to 2t however, 3x512 isn't booting up at all. The system defaults to even lower rated timings (2-3-2-5 and not 2-2-2-5) but still nothing.
Also, Idk if clearing the cmos helps since it defaults to AUTO for command rate, does that mean it'd dynamically change and detect it to 2t timings on an initial boot up, or just choose a default value at the beginning? So idk if it's my ram or mobo, but I usually setup the bios with a working set (like 2x512) set it to 2t, and try to stick the 3rd stick with that slight change, but still no avail.
Long story short, is command rate the only major timing that influences whether more than 2x512 sticks can be used? Or are there other ones that'd help it as well. I understand that overall running more than 2x512, like OP experienced, he'll need to completely redo all the timings to get close to his old OC. But mine is kind of ridiculous, not even default timings are working with 2t :mad: