Verger wrote:
You can look up processor overclocks here.

http://www.cpudatabase.com/index.cfm?Action=search

Some processor families have had observable failure conditions.
Note that the entries in the cpudatabase are not always good for
the long term health of the processor. (And some entries in the
database are pure nonsense.) Each processor has a max Vcore listed
in the processor datasheet (which you can download), and some are
more sensitive than others to abusing that limit. For example,
a Tualatin (nominal 1.5V) would fry after about a month at 1.8V.
Some people have lost AthlonFX processors on S939, and the cause
is believed to be related to the difference between Vcore and Vdimm.
(Also, some Athlon64 processors display what seems to be electromigration
failure, a gradual loss of overclockability.) So when you start an
overclocking project, it is a good idea to review the available
results from other enthusiasts.

"Sudden Overclocked Northwood Death Syndrome"
http://www.xbitlabs.com/news/cpu/display/news6375.html

For the really hot processors, sometimes the limits can be
thermal (you can no longer cool the processor well enough
or you fry the Vcore regulator). For example, the Pentium D 805
draws a tremendous amount of power if you run it at 4GHz (a
couple hundred watts). Rather than the processor failing, it
might be the motherboard that dies first. Some D 805 projects
got so hot, they melted foam placed underneath the processor
board, in the Vcore regulator area, while doing overclocks
on a table.

For my overclock on the computer I'm typing this on, my results
were rather obvious. Part of the frequency versus voltage
curve was rather gradual, and then I reached a point where
I could raise Vcore right to the datasheet limit (a "wall" so to speak),
and it wouldn't go a single hertz faster. That made the decision
as to what the operating point should be, rather obvious. No
point in cooking the thing, using more Vcore than really helps.
Other processors will tempt you with a more gradual curve, making
it harder to decide how much is too much. To make your own curve,
increase the CPU clock in steps of 5MHz, and only increase Vcore
if you cannot reach some stability criterion (some amount of Prime95
torture test time). Plot the points on a piece of paper, to see
the trend line.

Paul

"Verger" <nomail (AT) maildump (DOT) nl> wrote

possible. For the early P4s, I think the maximum temps were around 70-75c
where the processor would begin the throttle back. Temps rarely ever have
caused a processor failure, but overvoltage (vcore) can and will. Optimal
temperatures for your CPU would be under 60-62c under maximum load. You will
have other problems such as not posting or not loading the OS long before
you can damage the processor. What I would do is to take it as high as you
can and still stay stable at stock vcore and as soon as you have an issue
raise the vcore slightly until it becomes stable. Do all this in VERY small
increments while watching your core temperature. Idle temperatures may vary
depending on room temps, case airflow and the particular CPU cooler you
have. I use a program called Core Temp by Arthur Lieberman to monitor temps
and Orthos to load the processor. Both can be found easily with a simple
Google search at several different sites. Not knowing how overclocking
friendly your motherboard is I can't tell if your memory can be separated
from your system bus. If it cannot, that might also limit your ability to
get the maximum OC. There are a lot of variables, especially with the early
P4s that I wouldn't know about with the limited information I have about
your entire system.


Ed

Phil Weldon wrote:
That is a good point. All of the 1.7Ghz processors here are 0.18u, so that
leaves no doubt it is a Willemette.

http://processorfinder.intel.com/List.aspx?ProcFam=483

An example here, shows 1.75V nominal.

http://processorfinder.intel.com/det...px?sSpec=SL6BD

There should be datasheets for both a 423 package and a 478 package.
What I was able to find, is something for 423, but the same
technology limits should exist for both packages.

http://download.intel.com/design/Pen...s/24919805.pdf

The nominal listed there is 1.70V or 1.75V for that group of
processor, and absolute max is 2.1V. Looking at the VID table for
the processor, it only goes up to 1.85V. So your average motherboard
may have that as a Vcore limitation. Maybe the Vcore can only be
boosted to 1.85V. You'd have to check a BIOS screen or the manual, to
see if more volts than that are available.

Paul