Mark Mischke's Weblog

Undervolting a notebook

Many of us are familiar with overclocking a CPU - driving its base clock speed and/or multiplier higher than the rated specifications.  Overclocking is popular among folks who want to squeeze every bit of performance out of their rig.  It has its risks, but it's generally safe to do if not taken too far. 

Overclocking is possible because of the way CPUs are manufactured.  Many CPU dies share a single silicon wafer during the manufacturing process.  The exact number depends upon the size of the wafer and the size of the individual dies.  After fabrication, the wafer is tested, as a whole, and the dies are given specifications corresponding to the lowest common denominator.  One bad die lowers the ratings for its brethren, who may be capable of higher performance.

Marketing is another factor.  Intel might get so good at cranking out 3.6 GHz-capable Pentium 4 wafers that they're not flagging any as 3.2 GHz.  They still need to _sell_ 3.2 GHz chips, so that 3.2 just might be a 3.6.

If you try to overclock a 'bad' die, you might fry it or at least lock up your machine.  On the other hand, if you overclock a die that's been underrated, you might have some headroom to play with.  Don't get me wrong.  Overclocking can cost you a CPU and sometimes even add-in cards which may be sensitive to CPU bus speed.  Less is more, and you have to be willing to replace your hardware if it gets smoked.  Plus, overclocking may shorten the lifetime of a CPU and/or cards.

So, we've covered how some CPUs are capable of more performance than the packaging might lead us to believe.  These CPUs may also be driven at lower voltages with no loss of performance.  Lower drive voltages translates directly into less power draw, longer battery life (for notebooks) and less radiated heat.  The CPU is still running at its rated clock speed and multiplier, so there's no slowdown.  The trick is to find out how low you can go with the voltage without crashing.  There are two tools which help with this: RMClock and Prime95.

RMClock lets you mess with all kinds of CPU parameters (voltages, multipliers and the like) and Prime95 runs torture-tests.  The trick is to NOT set RMClock to auto-start until Prime95 can run for a good half-hour without locking up your machine.  Some say to notch down the voltage until you have problems and then kick it back up one step.  Maybe that's good advice for a P4 Mobile heat box, but I'm kinda conservative with this stuff (and I have a Pentium M).  I set my low-end voltage to 0.892V @ 6.0x (0.988V stock) and my high-end to 1.148V @ 18.0x (1.34V stock).  I haven't yet defined any mid-range values.

I'm intentionally going light on the details because you want to read this before doing anything.  It's important to understand what's going on, and the article is a very comprehensive introduction to the subject.  Good luck!

Some guys just don't get it

You abuse your wife.  She cuts off your penis.  Wake-up call, right?  For most guys, it would be.  John Wayne Bobbit seems to be a little slow on the uptake: http://www.cnn.com/2006/LAW/02/08/bobbit.acquittal.ap/index.html.

How many subsequent abuse charges has this freak had filed against him in the 13 years since his anatomical modification?  I recall at least a few.  Now, his _third_ wife is kicking him to the curb because of it  He's only 38.  Ten bucks says he gets it lobbed off again in his lifetime.  What a loser.

Cell phone hacking

We recently upgraded our venerable LG VX4400 cell phones to Motorola E815s.  The E815 is digital-only, so this is a bit of a leap for me.  I've long felt that analog fallback was essential, given that I like to spend time off the beaten path.  My stance is softening a bit.  Five years ago, a reliable cell signal, analog or otherwise, couldn't be had on I-93 north of Concord, NH.  Nowadays, I get a reliable digital signal from Concord all the way up into the mountains.  I suspect that other fringe areas will be following suit, and no one is putting up new analog transcievers anymore.

I love the E815.  I never knew that I needed a camera/video phone until I had one.  Now I can pix msg Ali when I'm in the supermarket looking for obscure vegetables which I've never seen or heard of before (some of which, I'm convinced, don't actually exist).  Likewise, she can spend a day furniture shopping and spamming me with pictures of potential home additions.

The coolest thing about Moto phones, IMHO, is the aftermarket support and the hackability.  The LG was a fantastic phone, but accessories were sparse and unsophisticated.  Accessories for Moto phones abound, ranging from the mundane to the esoteric.  Plus, there are communities of dedicated followers who share information on exposing undocumented and factory-disabled capabilities of Moto phones.

A 'Net search can turn up the tools required to reprogram Moto phones.  These are the same tools used by Verizon techs to update firmware.  I was able to locate these tools and the latest firmware.  This created a quandry for me.  I had the tools and instructions for updating the firmware myself, and I wanted the new features and bug fixes it offerred.  If I killed my phone in the process, I'd have to shell out for a new one, having blatantly voided my warranty.  On the other hand, I didn't want to wait an hour in the Verizon store or risk them pooching my phone (happens all too frequently, based on what I've read in the forums).  The Call of the Geek took over this morning and I flashed the phone myself.  Took about five minutes and everything worked perfectly.  I had to reset all my customized settings, but that took all of ten minutes.

After that, I used the Moto mobile Phone Tools (MPT), which I purchased, to sync selected Outlook contacts and calendar entries.  Now I can use my phone as a lightweight PIM - something I've wanted to do for years!

I haven't applied any of the feature hacks yet, mainly because I haven't seen any that I absolutely must have.  After doing a successful firmware upgrade, I don't fear feature hacks at all.  They're very easy to undo (whereas a firmware upgrade is not).  The one feature I was eyeing was the ability to transfer files to and from the E815 via MPT.  I discovered that I can e-mail wallpaper images and ringtones to my phone, and I don't change these very often, so my indirect workaround suits me fine.  Rumor has it that the E815 has hidden Java functionality.  If I can turn up more detailed information, I may enable it.  It'd be cool to be able to create my own apps for the phone - esp. since it's got a built-in GPS.

Ali wants her phone upgraded, too.  We'll see if she lets me do it or if she goes to Verizon.  She's less of a techie risk-taker than I am.  I'd never blame her for not wanting to chance her geek husband frying her primary means of communication (we don't have a land line).  But I will offer.

UPDATE: Ali did let me upgrade her phone after I agreed to shoulder half the potential replacement cost.  She gets mega geek-props.  Now I'm two for two.