How is this possible that the user with this question only has that little reputation? I've checked his site and he doesn't have a lot of downvotes or bounties.
I'm not sure if it applies to the specific user this question is about, but apart from what's already mentioned in the previous answer and/or question, these could be other reasons why a user's total reputation appears to not correspond to the total reputation points by various votes on all of the user's posts:
- posts for which the "community wiki" option is enabled do not generate any reputation points anymore (not for upvotes, not for downvotes).
- a user who downvoted (non-wiki) answers, and which are not deleted (yet), will have lost 1 reputation point for each of those downvotes. But these are not shown, by design, in the user's reputation history.
- for each suggested edit (except meta sites), and up to 500 of them, the user who suggested it earns 2 rep points. So without even 1 question or answer posted ever, a user may have already gained 1.000 points.
- association bonus adds another 100 points with no voting involved.
- when an upvoted answer is deleted, and it was posted long enough ago, the reputation points earned from such answer are not always deducted again (not sure about the exact criteria though). Such delete may have been caused by a delete of the question it was related to.