Damage rollover is around 83 or 84k PER ELEMENT and PER FRAME. Also, there was actually no damage cap/rollover until a certain patch. This was one of the exploits in the mod Median, where some people kept earlier d2 patches so that their damage would not roll over on some of the big hitting spells. 1.10 actually may not have a damage cap and it could be 1.11 that instated it. I'm not sure on it but I remember reading that older patches never had a damage cap, and I think 1.10 falls in that category.
edit: The following link will bring you to a thread on the Median forums. It is a "short questions" thread where people look to get quick answers. Halfway through the first page, someone asks about the damage cap. A few posts below that, another member answers that question. The number given was 82k, but I've heard 83 and 84 both being mentioned as well at different times and on different forums. In any case, it seems that my hunch of there NOT being a damage cap in 1.10 was correct.
http://modsbylaz.14.forumer.com/viewtop ... damage+cap