Hello.  Still more investigation reveals that my second post on this
topic about what's going on is wrong.  What appears to be happening is that
when the card is heavily loaded, i.e. processing enough requests to
generate 1200 interrupts/sec, or so, the card, or the motherboard, or
something, stops generating interrupts.  At least the output of vmstat -i
indicates that the number of interrupts coming from the card goes to 0,
and, then, after a long time, they start trickling in again, but very
slowly, and never with any regularity until reboot.
I've tried these cards with a couple of different motherboards, and the
behavior seems to be the same on each.
Anyone else seen this behavior?  Any ideas for a work around?  I'm not sure
I understand where the interrupt enabling code is for this card, and how to
reset it.
-thanks
-Brian