I purchased a DP43TF about 4 months, and have been running 4gb of OCZ PC2 6400 RAM in it flawlessly. I got the itch to upgrade to 8gb and therein lies the problem. At first, I bought a pack of Corsair XMS2-6400-4gbKITDDR2, which shows compatibility here http://corsair.com/configurator/product_results.aspx?id=613733#other_modules That didn't work, I kept getting the 3 beeps until I removed the new RAM. I tried replacing the old RAM with the new RAM, and it worked. I manually changed the memory settings to 5 5 5 10 and 1.8, and put the old RAM in, 3 beeps. I raised the voltage up to 2.2, 3 beeps. Ok, maybe I need the same RAM in all slots. I trekked back to the store, and was lucky enough to find the same OCZ RAM, and installed it, and 3 beeps. I'm running the latest bios, and have tried the automatic RAM settings, as well as setting it manually to the correct timing. Can anyone help?