Out of curiosity, did you try booting the unit with one stick of RAM first and let it auto-detect speeds/etc., then populate the rest? I had to do that recently when upgrading RAM as it would absolutely refuse to post, beep, blink, make me coffee, or anything else until I removed 3 of the 4 and left just slot 0 installed. Once it booted, I was able to power it off and install the rest, no muss, no fuss.