I had a older computer running three of the blue cherry cards with 12 cameras, there was no problems but it ran at 110% all the time so it was a pain to print pictures and they were so small as to be useless. So I upgrade the MB, CPU and memory.
Now it drops the middle four cameras all the time. Restarting zoneminder solves the problem for awhile. I also increased the image size form 320x280 to 420x315 wondering if that effects things?
I switched the cards around and that didn't help.
Running; mint 9, amd cpu, asus MB,