what's the difference between a socket 939 opteron and a socket 939 athlon 64 cpu?

Answer 1

Opterons typically have more cache and will perform slightly better than a similar speed Athlon 64. They were released on the socket 939 interface, though they were originally made for the socket 940.

The main difference is that the 939 doesn't require registered (buffered) DIMMs like the 940 Opterons do.

http://www.theinquirer.net/default.aspx?article=28369
http://www.simmtester.com/page/news/shownews.asp?where=533424&num=8059

Answer 2

are opterons socket 939...i thought they were 940 and athlons were 939...i know my older computers processor was an athlon fx-51 processor (the first of its kind) and it was 940 and ran on an opteron mobo. they have changed all the later athlons to 939 but mine was 940