Dear gentlemen, I've just tried looking at the CPU temperature via coretemp.ko on some SandyBridge CPU's. I have a desktop-grade Core I3 at 3.3 GHz, and a mobile Core i5 at 2.5 GHz. When I flip the CPU from "pretty much idle" to "each core running a cpuburn instance", the temperature reported by coretemp *jumps* up in a second. On the desktop CPU, the jump is about 10*C. On the mobile CPU, the jump is about 25-30 *C ! It jumps up in a second after I launch the software load - and then it proceeds to gradually inch up, as the massive heatsink starts to warm up a bit (perhaps another degree C in twenty seconds to a minute). Should I look for some thermal mischief in my system? Or, do the SandyBridge CPU's indeed "precompensate" the temperature reading based on instantaneous power consumption? I.e., is the "digital thermal sensor" more like a "fan control hint with a strong feed-forward component", rather than a half-decent thermometer? I've noticed already on some recent 45nm Core2 CPU's (on a gigabyte motherboard) that the fan control feedback loop responds magically swiftly to me launching some software load. I know that modern SuperIO chips (containing PWM fan control logic) can take the CPU temp value straight from the CPU (perhaps mediated by the south bridge), using a digital link called PECI. I also know a bit about the autonomous fan control algorithms implemented in chips by ITE and Winbond(Nuvoton) - I've played with these before. If indeed the CPU's DTHERM sensor would "bump up the reading" in response to power consumption, that would explain the swift modulation of fan speed based on instantaneous CPU load... Any comments are welcome :-) And, thanks for the providing the blessed coretemp.ko in the Linux kernel. Frank Rysanek _______________________________________________ lm-sensors mailing list lm-sensors@xxxxxxxxxxxxxx http://lists.lm-sensors.org/mailman/listinfo/lm-sensors
