Newsgroup: it.comp.hardware.overclock
Titolo: Intel bloccati: che sia meglio il K6??

Ecco le ultime da 
www.tomshardware.com
 e da PCWorld:
Tutti gli MMX e PPro in circolazione hanno i pins del moltiplicatore
bloccati, cioč si possono cloccare solo agendo sul bus speed, poco
quindi.
D'altra parte so che i K6 non si cloccano bene quanto si e' fatto finora
con gli Intel, perche' sono gia' spinti e si scaldano di piů.
Qualcuno ha suggerimenti per la mia prossima CPU?
Important News for Overclockers
              Quite a lot of time has passed since my last update of the
Overclocking Guide and now some
              really important things happened, which urged me to write
something about this topic.
              Although I never included it in my Overclocking Guide, the
Pentium II is a wonderful CPU to
              overclock. All PII 266 CPUs that I came across worked just
fine at 300 MHz and as long as you
              cooled the chip well enough, they even run at 337.5 MHZ,
(4.5x75 MHz).
              A simular thing used to be true for the Pentium MMX CPUs,
even Pentium MMX 166 CPUs ran
              just fine at even 233 MHz after simply changing the
multiplier.
              The Time Has Changed
              For a several weeks now it looks as if Intel has an
excellent yield in the production of the
              Pentium MMX as well as of the Pentium II. This means that
probably 90% of the produced chips
              are of top range spec, meaning that Intel almost only
produces Pentium MMX 233 and Pentium
              II 300 CPUs. However, since a lot of people are still
asking for Pentium MMX 166 and 200
              CPUs as well as PII 233 and 266 parts, Intel has to mark a
lot of faster parts slower than they
              are in reality. Now here the overclocking issue comes in.
Intel is aware of the fact that people
              know about overclocking and they want to get top money for
top performance. I never thought
              of having a reason to buy a PII 300, because the PII 266
was just as good. Lots of you advised
              friends to buy a Pentium MMX 166 instead of a 233, because
it ran the same and indeed it was.
              Intel doesn't want this, as everyone can imagine. Hence
they did something that they've done
              once before in the past. I'm sure that lots of you still
remember the Pentium 133 SY022 CPUs,
              which wouldn't recognize any multiplier setting higher
than x2. Intel disabled the higher multipliers
              by just not bonding one of the multiplier pins. That is
the same they are doing now. Please
              understand that this is some kind of touchy thing when
chip production starts. You can only test
              a CPU after it's packaged, which means after bonding. As
long as you are not producing many
              fast chips like e.g. a Pentium MMX 233, you are taking the
risk of wasting some high end parts
              by bonding them to only 166 or 200 MHz versions. That's
why Intel never has this 'overclock
              protection' in newly released chips. However, when the
yield of high end chips is really high,
              even higher than what the market wants, you can afford
castrating fast parts to slow ones by
              just bonding it.
              The result of this is that Pentium MMX 166, Pentium MMX
200, Pentium II 233 and
              Pentium II 266 CPUs cannot be overclocked via higher
multiplier settings anymore. This
              seems to be the case for the last 4 to 6 weeks, which
means that there are hardly any
              'overclockable' Intel CPUs on any of the shop shelves
anymore. Only a shop that's hardly selling
              any and that's got a CPU lying around for a long time
might have one of the 'gems' left.
              This restriction of the multiplier settings does of course
not affect the overclocking via higher
              bus speeds. You can still run a PII 266 at 300 MHz, but
it'll have to be 75 MHz x 4, because 66
              MHz x 4.5 won't work anymore. You can even push it to 333
MHz, but this means using 83 MHz
              bus speed, which runs only in very few boards with very
few RAM types and hardly ever with
              AGP graphic cards. Forget about 100 MHz in 440FX or 440 LX
boards. I've tried it with the
              extremely stable LX6 from Abit and with the best memory I
could get. 83 MHz is fine in the LX6,
              but forget the 100 MHz it offers. The same is valid for
the latest versions of the Asus LX boards
              that also offer you 100 MHz bus speed - it just doesn't
work. 75 MHz are fine with Pentium II
              CPUs, 83 and more should rather be left alone, because the
system gets too unstable and AGP
              graphic cards don't like an AGP bus running at 83 MHz
instead of 66. 100 Mhz should be left to
              the upcoming 440BX boards and the 'Deschutes' Pentium II
CPUs that are designed for 100
              MHz bus speed.
              Socket 7 CPUs at 83 are easier to handle, so there's still
a chance of running a Pentium
              MMX166 CPU at up to 208 MHz and a PPMT 200 at up to 250
MHz, c't Magazine may scream
              and shout, but ten thousands of people that run 83 MHz
reliably and stably for months can't just
              be wiped away and it even works in Germany, not only
outside this wonderful country.
              One last word to the castrated Pentium II 233 and 266
CPUs. This is the first Intel CPU which is
              'assembled'. This brings the thought near that the
disabling of the higher multiplier was not done
              inside the actual chip package, but somewhere inside the
cartridge. It could be possible that this
              castration can be 'reversed' after openng the cartridge
and finding the right spot. If anyone of
              you is willing to try ... let me know and I'll publish it.
It's just a damn problem to open that
              %^&*$#@ cartridge ...
              And What about the Others ... ?
              Well, what about the AMD K6 and the Cyrix/IBM 6x86MX ? If
you let me start with the 6x86MX,
              I have to tell you that especially Cyrix is selling their
6x86MX chips pretty close to the margins,
              as well known from the past already. They came up with the
- with all due respect - crazy idea
              of selling parts with different specs under the same name.
You can get PR166 CPUs at 2x66
              and 2.5x60 MHz, PR200 CPUs at 2x75 or 2.5x66 MHz and PR233
CPUs at 2.5x75 or 2x83
              MHz. These CPUs with the same P-rating are actually not
performing equally, but who cares?
              Now I came across cases where you couldn't even clock a
PR200 CPU at 2x75 MHz to 2.5 x 66
              MHz, which is slightly faster. Hence forget about
overclocking unless you got a nice PR233 at
              2.5 x 75 MHz, since then you might have a chance. IBM is
unfortunately under the threat of
              conformity with Cyrix and rumors say that IBM is selling
their chips the same way against their
              own believe ... well, well.
              This leaves AMD's K6 as the only real overclocking champ
and as long as your K6 is real,
              you've got a good chance to overclock which ever way you
like, either with multiplier increase or
              with higher bus speeds or with both. However there's a
little problem. AMD doesn't seem to
              care much about the fact that remarking their chips can be
done by a six year old child. There's
              only some paint printed on the aluminium heat sink
attachment, which you can wipe off with
              several different chemicals. Printing a new marking on the
'naked' CPU is not too hard to do.
              This makes a K6 233 out of a K6 200 or even K6 166. Be
careful with that, examine the printing
              very carefully. If it's done well, you won't have a chance
though. The incidence of remarked K6
              CPUs is cerainly higher than you think, and most reports
about 'unoverclockable' K6 CPUs are
              due to remarked 166 version, marked to a K6 200.
Intel Modifies CPUs to Prevent Overclocking
by Brian McWilliams, PC World News Radio
December 2, 1997
We brought you the story last week about the growing popularity of
overclocking PCs. Overclocking
involves changing some jumpers on a PC's motherboard to speed up the
processor by 33-MHz or so.
AMD, Intel and other processor vendors have always frowned on
overclocking, saying it pushes the CPU
beyond its specified limits. Now Intel may have decided to back up its
warnings with concrete action. The
company has reportedly begun bonding the multiplier pins on the CPU to
make it impossible to overclock
its new Pentium with MMX and Pentium II chips.
Intel spokesperson Manny Vara wouldn't confirm the reports, but he did
say that the chipmaker is
concerned that some unscrupulous companies may be overclocking its CPUs,
relabeling them as faster,
and selling them in systems.
Vara said that restricting the multiplier settings on a CPU protects
buyers of new PCs, even if it frustrates
power users who want to get something for nothing. So far, AMD's
processors do not restrict users from
changing the CPU multiplier settings.
Although they may have lost the ability to overclock Intel CPUs,
die-hard speed freaks can still overclock
the system bus on Intel machines. But that practice, like overclocking
the CPU itself, has a number of
potential problems.

 Ecco le ultime da 
www.tomshardware.com
 e da PCWorld...
Grazie Luca per il tuo contributo, ma ti sembrava il caso di copiare
tutto
l'articolo di Tom? Non era meglio metterne l'URL così da evitare di far
scaricare a tutti un messaggio così lungo?
Ciao,
paolo