Wednesday, March 17, 2010

Further Education with juno

Now that I've been working with juno for a few weeks, I have a few updates.
  • I found the setting that preventing booting and locked me out of the BIOS. Twice. If I chose "AHCI" or "Linux AHCI" instead of "IDE" for the SATA interface -- that which talks to the various storage devices, including the optical drive, hard drive, and SSD -- I got my unbootable lockout. So, having had to open the case and reset a jumper twice to get back to defaults, I know to avoid these! (Theoretically they should work. Theoretically.)
  • The memory (RAM) was rated at 1.8-1.9 volts. The motherboard auto-chose 1.9 volts. I decided to manually set it to 1.8 volts, and it still works fine, even under the stress test. The idle power consumption edged down from 30 watts to 29 watts.
  • It looks like the CPU temperature reporting isn't fully locked at 42°C, but rather won't report anything less than that. During some of the stress tests I saw brief flickers up to 43°C, leading me to believe that the sensors are alive. This summer, when the room temperatures are 5°-6°C higher than now, the sensors are more likely to wake up during the stress tests.
  • I've been slowly experimenting with overclocking -- running the CPU and memory at faster than the rated speeds. The bog-standard default for juno's equipment is 2.93GHz for the CPU, and 800MHz for the RAM. Gradual bumps in speed have been followed by stress testing, so that I know sooner rather than later that it's gone too far. By now, juno is up to 3.16 GHz / 864 MHz. I've left the CPU and RAM "linked" -- overclocking in tandem. If I care to, I can unlink them, so that, for instance, I could continue to bump the CPU speed without taking the memory further than it can go. That juno can accomplish this with the -.10v undervolt of the CPU and the 1.8v setting on the RAM shows how some parts are binned by demand rather than quality. That is, my CPU may be a perfectly good 3.06 GHz or better part, but Intel needed more of the less expensive 2.93 GHz parts to sell, and fixed it as such. In any case, I plan to be conservative, and back off a couple of steps when either 1) the stress test starts to throw errors, or 2) the power consumption starts to climb more than a watt or two.
  • I may also experiment in future with the power consumption response to deliberately underclocking the system.
 

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