I have an Asus board was installed and PR5 PRO 2 modules of 2GB Kingston 800 Mhz.
Total I say I will buy a couple more and I caught exactly the same. I'm going to mount and nothing, blue screenshots in XP and Vista and the memory test detects error. Takes one to prove if he was fucking and functioning properly. Vista x64, I found 6 GB of RAM. Camvio module to see if it actually was broken and everything seems to work well, I still detected 6 GB.
The problem comes when I put the two modules for a total of 8 GB, it seems impossible to make them work, I get blue screen and I crash. When you try to reinstall the CD also comes screenshot of view.