Jeff Liebermann wrote:

Out of about 7 machines, I
managed to reverse the caps on 4 of them. All had the silk screened
stripe marking the "+" end instead of the usual "-" end. I didn't see
the "+" silk screened marking or bother checking the square pad, until
Phil Allison pointed it out in the first photo.

BTW, not all Dell mobos are marked that way.

Do you mean you don't write a red dot next to the positive lead when
you remove each capacitor? I do that because I've come across
circuit boards that were marked wrong.