This is due to the fact that your RAM's SPD data is programmed for DDR2-1066 for whatever timings, and I can guess that this requires more than 1.8V to POST......1.8V is the default voltage for DDR2. I encountered the same issue.
YOu can do two things to avoid this DETDRAM issue:
1) DOwnload
this app and reprogram your SPD data to default to DDR2-800 or 667 5-5-5-15 and change the timings/frequencies manually in the BIOS after POSTing and setting the proper voltage
2) Buy a stick of value RAM at a local place for $25 or so and put this stick in when you flash a new BIOS or have to clear the CMOS.....POST with this RAM, then change the voltage, then save and reboot, POST, then enter the BIOS and hard shutdown, then install your high performance RAM.
I am currently going with #2 for my RAM until I load XP to reprogram the SPD data. (driver isn't signed, so it doesn't work with Vista x64)