It seems that your memory is rated at the right voltage (1.65V), are you putting all 3 sticks in at the same time? The p55 chipset is a dual channel solution, not triple channel like the X58. So you can only have 1, 2, or 4 sticks installed at the same time, not 3. I'd start by only having one stick installed in the right slot (DIMM 0, Slot A) first blue one from the cpu socket and then go from there. If you are still getting 3 beeps and not even POSTing then your probably have a bad motherboard
I had the same problem, It turned out to be a bad video card. I followed the same logic as you based on an error code description from one source (can't remember where) and found a second source that described it as a video card problem.