Sonnet Tempo E4i, E4P “interrupt storm”
I have both the Sonnet Tempo E4i and E4p installed in my PowerMac Quad. If you’re purchasing an SATA PCI-Express card for your PowerMac G5 dual-core (PCI-Express slots), you should be aware of a problem that occurs for me on a regular basis with these cards, which I’ll call the Interrupt Storm problem. It occurs sporadically, with one card or two.
The problem manifests itself as 100% CPU usage of one of the cores. On a Quad, the fans ramp up slightly; on a dual-core machine (2 cores total), you might notice an impact to your work speed. If you use Activity Monitor’s history graph, you’ll see that the CPU time is all red (system time), and is being used by “”.
The problem is at least a nuisance, and can be resolved by putting the machine to sleep, then waking it up. However, for those who start long-running “money” jobs, such as video rendering, this could be a very serious problem, because it “steals” an entire core’s worth of CPU. On a Quad, losing 25% is an annoyance; on a lesser machine losing 50% could be serious. Worse, it impact disk I/O speed substantially.
