Re: XPS 720 fans blowing at max, hard drive wrecked
If the memory controller is having a problem getting the correct voltage or there are conflicts in the sticks, all kinds of crazy things can happen. You should be able to run 4 gigs at 1066 but i am unsure about the reapers. For the reapers to run at full specs they need 2.1v applied. most of the time the board can provide this but due to the not tuning capabilities of the bios any other ram tweeks are out of the question.
You can try other mfrs of ram if you are looking for the 1066 speed.