As seen below (Figure 1), I have two 512MB sticks in alternate slots (one channel) and a 1GB stick in one of the remaining slots (a different channel). This is on an Asus P4P800.
When I boot, it says that it is running in Single-Channel or Virtual Single-Channel mode. I have searched everywhere but cannot find any information on what the heck “virtual single-channel” is. The only references that I can find are simply mentions of it by people trying to get dual-channel working as opposed to wanting to know what “virtual” means.
My best guess is that it is a synonym for either asymmetric dual-channel (which seems to apply here) or dual-channel interleaved (which does not). I cannot find anything about the P4P800 supporting either of those modes however, so I really have no clue what virtual single-channel could be.
Figure 1: RAM configuration on a P4P800
[ 512MB ] (Blue) [ 1GB ] (Black) [ 512MB ] (Blue) [ ----- ] (Black)