Hmm, there actually is a comment on the ASUS website: 'Earlier BIOS may boot up with single channel memory only'
http://support.asus.com/cpusupport/cpusupport.aspx?SLanguage=en-us&model=A8V%20Deluxe
Apparently the problem is that the BIOS on the support CD is too old to run certain newer CPUs in dual-channel mode, that's why removing one of the DIMMs helps (sometimes).
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Asus comment
Hmm, there actually is a comment on the ASUS website: 'Earlier BIOS may boot up with single channel memory only'
http://support.asus.com/cpusupport/cpusupport.aspx?SLanguage=en-us&model=A8V%20Deluxe
Apparently the problem is that the BIOS on the support CD is too old to run certain newer CPUs in dual-channel mode, that's why removing one of the DIMMs helps (sometimes).