Attached are images of the 512 MB, ECC, REG modules I tried. Both are PC133. Unfortunately for the modules on the left, SPD has CL3 encoded for PC100 speeds, while the modules on the right have CL2 encoded for PC100 speeds. Nonetheless, the set should work fine at PC100 CL3 speeds. Each module works if the total amount of memory is limited to 1792 MB.
The attachment 512MB_ECC_REG_PC133.JPG is no longer available
Next, I tried 1 GB modules. I can use single 1 GB sticks, but once I install 2 GB, the system beeps as before. I tried these sticks:
The attachment 1GB_ECC_REG_PC133.JPG is no longer available
The installed graphics card is a Diamond Viper V770D AGP 32 MB card. Maybe I need to have only a 1 MB graphics card for 2 GB to work? Or maybe I need to disable the onboard SCSI BIOS? Or maybe the board is very particular about which modules will work? Another idea is that there is some current limit being imposed by the onboard regulators and 2 GB is over the limit. I recall running into this problem when I tried to run 2x 700 MHz, 2M processors. It would work fine with 1, but not with the pair. Hence, my system is using 500 MHz, 2M processors. I think it can get away with 2x 550 MHz 2M, but I need to check that again.
Plan your life wisely, you'll be dead before you know it.