SUMMARY: Penciling in the L1 bridges works sort of OK; the reason is that graphite is a RESISTOR, not a great conductor of electricity.
I received this email from Walt:
Just a brief comment on your observation that sometimes connecting the L1 bridges won’t work. I have an Epox EP-8KTA+ with a 750MHz T-Bird. I tried the “pencil trick” (using a standard #2 lead pencil requiring manual sharpening) 3 times on my L1 bridges without success. Reseating the cpu and booting sent me to my standard 7.5X multiplier, no matter how I had configured the mobo multiplier settings.
I decided to have one final go at things, but this time I bought myself a .5mm mechanical pencil, and paid careful attention to the fact that it included #2 lead. There were maybe a dozen different brands of mechanical pencils at my local drugstore, and I noted with interest in studying the “specs” for them that many of them did not provide a lead # (2,3,4, etc.) at all, but rather simply stated that they used a newer “high polymer” lead material.
Just speculating, but I wonder if the high polymer lead is indeed less conductive than the older lead composites identified by the tradition # scale. I wonder if some people haven’t been using these pencils to do the bridge with little success. Just a thought.
Anyway, after getting the pencil I also purchased a cheap magnifying glass. When I got home and removed the cpu and inspected what I had done previously, with the magnified aid I could see how I had plainly missed the bridge contacts! To my naked eye this was not apparent at all, amazingly (I figured, wrongly, that looking at it an inch away was as good as a magnifying glass.) So I cleaned the chip with alcohol and tried again, this time with the aid of the glass and the .5mm #2 lead pencil.
It worked! I am now running at 850MHz at standard voltage, contemplating the wisdom of increasing the voltage to 1.85 to get to 900 or higher. So your comment about “inadequate conductivity” between the bridges was exactly right in my case.
I’ll bet I’m not alone in this instance, and as of now I think a magnifying glass is SOP for unlocking the multipliers by the L1 bridge connection procedure. Most of your readers were probably ahead of me on this score, but you might want to pass this along just for people who might be tempted to think their unaided vision is much better than it actually is for this type of precise close-up work.”
Now I’m sitting here fighting a rotten cold and not feeling like doing too much, so I start to browse around the web about “lead pencils”. Turns out what we are all doing with pencils is adding a resistor to the L1 Bridges! Maybe some of you knew that, but I did not. Here’s one link with an explanation:
“The lead in a pencil often contains carbon. This material is used to build resistors. Like a resistor, the lead allowed electrons to pass through it, but not very easily.”
Well then, depending on the pencil’s graphite mixture, some are going to be OK and some not so OK. So now, being curious about this, I round up some pencils and tested their resistances with an ohm meter:
|Dixon Ticonderoga 1388-2|
|Berol Arcadia 167 #2|
|Faber American #2|
|Sanford Eagle HB #2|
Now THAT’s some difference! Using the Sanford is about the same as using a 100 ohm resistor instead! Even more curious, I surfed around and found this:
The more graphite that is introduced into the mixture the softer and blacker the pencil will become: this group ranges from B up to 6B; the latter degree has a far greater proportion of graphite to the clay and is much favoured by artists.
At the other extreme the more clay the harder the pencil; these are manufactured from H up to 9H. The 9H pencil contains a very large proportion of clay and very little graphite and is used mainly by stonemasons and steelworkers.
So, turns out those hard #3 or 4 pencils are definitely not ones that should be used – clay is not known for its capacity to conduct electricity. I would guess the best bet is a nice soft #1 from Dixon Ticonderoga.
Who would have thought that overclockers would be pencil connoisseurs?
PS: If you are interested in some pencil stuff, the following links might be of interest:
And a couple of tidbits:
“Pencils – Black Lead – Advantages: Very long storage life, exceptional value for money, wide range of degrees from the ultra soft 6B to the hard wearing 6H.
Drawbacks: Requires additional sharpening tool and shavings need disposing.”
“I am the pencil, the first chronicler of new-born thought. I come from the sleeping graphite beds, and the balsamic frills of kingly cedars. In my heart, I carry the black carbon of Pluto’s world-half-brother to the diamond.
“I memorandum the business of continents, and strike the trial balance in the traffic of nations. I am the hub in the wheel of theory – the keystone in the structure of fact.
“I note the doings of the world in the dizzy hours of the morn while presses wait like couchant beasts to fling my efforts to sleeping millions. I am man’s best friend. I am his only confidant.
“I am the major factor in the world’s great things, and millions of nervous fingers fondle me every hour. I make the creed of yesterday and the statute of tomorrow, and plan and perpetuate the accomplishments of man. With me the pale-faced scholar summons Grant and Lee and Moltke and Hannibal, and makes their phantom armies shake the world once more.
“I tabulate the passing of Kings and, alike, the date from the crucibles of wizard men whose alchemy distills new brews to baffle death. I trace the drunken letter of the child whose dimpled fingers try to ape the art of Spencer. I sketch the songs of the eager poet, and trace again the battle march of Alexander.
“I am the democrat, the whittled comrade of the ragged urchin, confidant of the diplomat, book-keeper of the lonely shepherd upon the mountainside.
“I am the cosmopolitan, known in every mart where money clinks, in every port where commerce spreads her sales, in every town and hamlet where the brain of man connives. I am the PENCIL and my mission is service.”
If you’ve read this far, I’ve tossed in this link for something different:
Here’s a riddle: ‘I am taken from a mine, and shut up in a wooden case, from which I am never released, and yet I am used by almost everybody. What am I?’