Hi
I guess I forgot to mention, I ran memtest86+ for all my modules and nada. The funny thing is, as I mentioned earlier, I can put any combination of three of the old and new sticks into any of the first two and third or fourth slots, and they all work, but as soon as I put the fourth one in, then two of them become unusable. And it's always DIMM's 1 and 2 regardless of which module was put where.
I doubt this is relevant, but despite being identical model numbers, the new modules are rev 3.13 while the old ones are 1.something.
I guess the next step is disassembling my CPU. As this is a somewhat involved procedure, the earliest I can report back is tomorrow.
Thanks.