> Yesterday I raised the clock to 3.4 Ghz and I set all voltages to "normal" and > it seems to run fine. I will have to check under really heavy load yet, I will > do that tonight. My motherboard has an option "power line load calibration", I > guess that has something to do with it :-) > > Interesting: I pulled out a "modern" (but cheapo, no fans) pcie vga card and > replaced it with a very old pci card (I guess from 1996) and that saves me 20 > watts! That's more power than I problably ever could save using C states! Yep, beware graphics card power. > BTW on my ancient athlon-mp board, I could enable c2/c3 (although not > supported by the bios) and that would save about ~40 watts of power. But it > looks I won't see such a difference on modern CPU's, maybe because of the > dynamic frequency scaling and enhanced c1? Is there anyone who can give me an > indication of what to expect in powersavings by c2-c7 on modern cpu's? On the mobile parts they used to publish the power limits for C-states, but I don't see these numbers in the core i7 datasheet... However, many have done comparisons of what you might expect for idle vs loaded power. eg. http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=3634&p=17 In general, I don't view it as a Linux bug that the MB's BIOS disables c-states when it is over-clocked. Indeed, it is quite possibly a BIOS feature. Len Brown, Intel Open Source Technology Center -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
