I originally built a system in November 2002:Motherboard: ASUS A7N8X Deluxe v0.6
CPU: Athlon XP 2800+ Thoroughbred
RAM: 1GB (2 x 512MB). No kits back then.
O/S: Windows XP Professional
A lot of people had problems with motherboards with the nForce2 chipset back then because it was real picky with RAM. There were no RAM kits back then so I had to buy good memory and hope for the best.
I had problems with the original motherboard so I replaced it a few years later.
This is the current configuration:Motherboard: A7N8X-E Deluxe v1.0
CPU: Athlon XP 2800+ Thoroughbred
RAM: 2GB Kit (2 x 1GB)
O/S: Windows 7 Home Premium
I was curious about your problem with 3 sticks of RAM so I decided to add a 3rd stick of RAM to see if I could get it to work. I used one of the original 512MB sticks of RAM I bought 11 years ago. I knew I would have a problem since the 512MB RAM was DDR333 while the newer 1GB RAM was DDR400.
The system crashed with the new RAM. Through experimentation (including a few BIOS resets) I finally found a combination of manual settings that worked. I used Memtest86+ to verify initial stability. I used Prime95 for over 1 hour to further prove stability.
The image I inserted shows the RAM I used, the sockets in the motherboard I placed the 3 sticks in, the BIOS changes I made for the RAM timings, and the results from CPU-Z.
Note that I changed the timings to match the JDEC #1 configuration for the 512MB stick. Also note the 2 sticks of 1GB RAM had to be slowed down to match the 512MB RAM speed.
I do not know if what I did will help you but at least it proves that 3 sticks of RAM will work in these boards. BTW, it would have been a lot less of a problem if all 3 sticks were identical. Since we are both mixing RAM that made things more complicated.