My situation i have a set duel channel 1 gig a-dat memory ddr 400 2gig total memory works for 3 years, still works great.
I bought the same memory, set duel channel 1 gig a-dat memory ddr 400 and installed them on my vista 64 bit system
the bios reads 4gig np but windows will not load (windows error recovery) no specific error listed. I then took out my original memory and left the new in the newly used duel chanel slots on my motherboard.
Both the new memory and the previuosly unused ram slots work fine. I have repeatly installed all 4 gig same problem (windows error recovery) and always
works fine with either set of in either duel chanels on my motherboard. I have windows vista 64 bit.