I tried a 1Gb Kingston RAM (667 ofc) on the motherboard and only 512Mb showed up when I started the computer. I turned off "Enable Core 2. CPU overclocking" from BIOS. Then it started up, shows "Memory loading..." and then it´s "Memory 1024000" something. Restarts, loads memory again and shows "Memory 512000" something. Boots up fine. Shows 512Mb.
There is no use when the max is 2Gb, I put in 2Gb, but it shows and runs like 1Gb. My guess is I really have to get DDR2-533.