C2D Overclocking Techniques Asus P5B-Plus

I read in another thread in this group that you should:

"Unlink the memory clock from the CPU clock and run the memory at its stock
specifications" (thanks to Phil Weldon)

In my P5B-Plus BIOS (after setting the AI Overclock to manual) I have a
setting for CPU frequency, adjustable in 1 MHz increments. This setting is
linked to DRAM frequency as any change in CPU frequency reflects as an
equivalent change in DRAM frequency.

To keep my memory in spec, I originally set my DRAM frequency to DDR2-533MHz
because I knew it would increase with increases in CPU frequency.
Presently, I've raised the CPU frequency from the original 267 to 333, which
has put my DRAM frequency at DDR2-667MHz.
That's a modest overclock for my 6420, now running at 2.67GHz.

Now that I've acquired a 3rd party HSF (the Intel HSF is barely able to cope
with the current settings), I'd like to raise the CPU frequency in small
increments, but I really prefer to leave my DRAM frequency where it is.

The only settings available for DRAM frequency are DDR2-533, DDR2-667,
DDR2-800, DDR2-889, DDR2-1067 and AUTO.
Unfortunately the manual does not describe the effects of using AUTO, but
that would appear to be the only possible way to unlink the memory clock
from the CPU clock, if AUTO somehow means set by interrogating the memory
modules themselves (used to be called "by SPD" IIRC).

Am I on the right track to decoupling CPU clock and DRAM frequency, or is
there some other BIOS setting I've missed completely?

TIA for any enlightenment/suggestions.

'Peter van der Goes' wrote, in part:
|I read in another thread in this group that you should:
|
| "Unlink the memory clock from the CPU clock and run the memory at its
stock
| specifications" (thanks to Phil Weldon)
|
| In my P5B-Plus BIOS (after setting the AI Overclock to manual) I have a
| setting for CPU frequency, adjustable in 1 MHz increments. This setting is
| linked to DRAM frequency as any change in CPU frequency reflects as an
| equivalent change in DRAM frequency.
|
| To keep my memory in spec, I originally set my DRAM frequency to
DDR2-533MHz
| because I knew it would increase with increases in CPU frequency.
| Presently, I've raised the CPU frequency from the original 267 to 333,
which
| has put my DRAM frequency at DDR2-667MHz.
| That's a modest overclock for my 6420, now running at 2.67GHz.
_____

Overclocking is a voyage of discovery. Different motherboard manufacturers
customize BIOS settings in different ways. Some chip sets allow setting
parameters that are not available when other chip sets are used. Generally
the motherboard manuals provided don't offer much explanation, and seem to
be the product of several translations back and forth among several
languages - and even different concepts of math B^)

Form a cursory look at the manual for your P5B Plus motherboard, it seems to
me that selecting a memory speed from the list under 'DRAM Frequency' in the
'Advanced Chipset Settings' page

[Auto]
[DDR2 - 533MHz]
[DDR2 - 667MHz]
[DDR2 - 800MHz]
[DDR2 - 889MHz]
[DDR2- 1067MHz]

sets the memory speed to specific frequencies that are not linked to the CPU
speed, with the [Auto Selection] possibly a setting to link the Memory Clock
to a multiple of the CPU Clock, probably 1:2].

I'd guess that you are wrong in assuming that increasing the CPU clock speed
increases the Memory clock speed UNLESS the 'DRAM Frequency' setting is
[AUTO]. The English version of the manual is ambiguous on this and other
points. There does not seem to be the flexibility in the BIOS settings
that, for example, the nVidia 680i chipset has for memory frequency where
any memory bus frequency can be set independently from the FSB frequency
(though there is some granularity.)

For your particular concern, I'd set the 'DRAM Frequency' to the
specification of your memory modules, and assume that the memory clock
frequency would be fixed. If you, after getting a stable CPU overclock,
wish to overclock your memory, it seems that only certain fixed memory speed
steps are avaliable in the BIOS. Perhaps the ASUS OS based overclocking
application has additional flexibility.

Try it and check the results.

Phil Weldon


"Peter van der Goes" <pvdg.RemoveThis@toadstool.edu> wrote in message
news:VGCgi.235360$NU1.216186@newsfe13.lga...
|I read in another thread in this group that you should:
|
| "Unlink the memory clock from the CPU clock and run the memory at its
stock
| specifications" (thanks to Phil Weldon)
|
| In my P5B-Plus BIOS (after setting the AI Overclock to manual) I have a
| setting for CPU frequency, adjustable in 1 MHz increments. This setting is
| linked to DRAM frequency as any change in CPU frequency reflects as an
| equivalent change in DRAM frequency.
|
| To keep my memory in spec, I originally set my DRAM frequency to
DDR2-533MHz
| because I knew it would increase with increases in CPU frequency.
| Presently, I've raised the CPU frequency from the original 267 to 333,
which
| has put my DRAM frequency at DDR2-667MHz.
| That's a modest overclock for my 6420, now running at 2.67GHz.
|
| Now that I've acquired a 3rd party HSF (the Intel HSF is barely able to
cope
| with the current settings), I'd like to raise the CPU frequency in small
| increments, but I really prefer to leave my DRAM frequency where it is.
|
| The only settings available for DRAM frequency are DDR2-533, DDR2-667,
| DDR2-800, DDR2-889, DDR2-1067 and AUTO.
| Unfortunately the manual does not describe the effects of using AUTO, but
| that would appear to be the only possible way to unlink the memory clock
| from the CPU clock, if AUTO somehow means set by interrogating the memory
| modules themselves (used to be called "by SPD" IIRC).
|
| Am I on the right track to decoupling CPU clock and DRAM frequency, or is
| there some other BIOS setting I've missed completely?
|
| TIA for any enlightenment/suggestions.
|
|