I would rather try testing with only a few cards to troubleshoot it.
could be power problem and/or temperature problem. Is the system motherboard (using risers ?) etc even compatible with that power drain. What about the PSU(s) ? how do you (externally) power all those cards (I guess you know that some power comes over PCI but the remaining part directly over the power cables from the PSU, so 2 possible points of failures) ?
Start with 2 cards, see how long it runs... add another card, see how long it runs etc... you will quiet quickly find out what happens and what the problem could be
could be power problem and/or temperature problem. Is the system motherboard (using risers ?) etc even compatible with that power drain. What about the PSU(s) ? how do you (externally) power all those cards (I guess you know that some power comes over PCI but the remaining part directly over the power cables from the PSU, so 2 possible points of failures) ?
Start with 2 cards, see how long it runs... add another card, see how long it runs etc... you will quiet quickly find out what happens and what the problem could be