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Memory bus speed

 
 
Ronny Mandal
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      07-22-2007, 07:34 PM
Hi!

Got some questions about memory and bandwidth:

I am currently running 4 GB og DDR2 PC8500 Memory modules on ASUS P5K.
That mainboard natively supports 1333 MHz bus frequency. THe MMs
supports up to 1066 MHz. But on the POST, the BIOS reports DDR-2 800
in Dual channel interleaved mode.

I've tried to set the freq. manually to 1066, but then WinXP did not
start.

Is there a correlation between voltage settings etc. when modifying
this value?

Hope someome here is able to help me, I do not wanna run my MMs in 266
MHz less than they're capable of.


Regards,

Ronny Mandal
 
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Phil Weldon
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      07-22-2007, 08:11 PM
'Ronny Mandal' wrote:
| Got some questions about memory and bandwidth:
|
| I am currently running 4 GB og DDR2 PC8500 Memory modules on ASUS P5K.
| That mainboard natively supports 1333 MHz bus frequency. THe MMs
| supports up to 1066 MHz. But on the POST, the BIOS reports DDR-2 800
| in Dual channel interleaved mode.
|
| I've tried to set the freq. manually to 1066, but then WinXP did not
| start.
|
| Is there a correlation between voltage settings etc. when modifying
| this value?
|
| Hope someome here is able to help me, I do not wanna run my MMs in 266
| MHz less than they're capable of.
_____

THe ASUS P5K is an overclocking friendly motherboard, so the manual should
explain the proper settings to set the memory clock speed to almost anything
you wish. However, if the manual is typical the manuals from ASUS, aBit,
.... the lanuaguage may be a bit difficult, as if it had been written in one,
translated to a second, proof read in a third, then retranslated to various
other languages.

I have an EVGA 680i motherboard based on the nVidia 680i chipset. In the
BIOS,
IF
disable SLI-ready memory
unlink the CPU clock and the memory clock
I can set the memory clock to almost anything. The resultant memory
setting is somewhat granular (the BIOS changes some memory speed settings
down by a few MHz.) The terminology used in your ASUS BIOS and manual is
likely different from that used by my nVidia BIOS and manual, so you will
have to puzzle out the differences.

I generally set my system (Intel 4300 / EVGA 680i / Patriot PC8500 DDR2-1066
2 X 1 GB SLI-ready memory) to
FSB = 1200 MHz
Memory Bus = 1200 MHz
Memory Voltage = 2.300
Memory Timing = 5-5-5-9.

In my system, setting the Memory Bus to 1200 MHz gives a memory clock speed
of 600 MHz, a 1:2 ratio of CPU clock : memory clock.

The Patriot Memory has extended SPD data that holds the settings for
DDR2-1066 operation since there are no standards yet for DDR2-1066 and
higher. The voltage for DDR2-1066 operation is 2.30 volts. I use that for
equivalent DDR2-1200 operation, and have picked timings that give stable
operation at DDR2-1200 equivalent operation.

Most systems from larger manufacturers use a 1:1 CPU clock : memory clock
ratio (the memory bus is 1/2 the FSB speed.)

Some (if not all) DDR2 memory rated DDR2-1066 or higher may require higher
than the standard of ~ 1.85 volts for DDR2 memory. If this is true for your
memory it may be why you can't boot into Windows when you set the memory
speed to DDR2-1066 equivalent. Look up the specifications for your memory,
read the SPD contents, and post the information here. Also, someone on the
newsgroup who also has an ASUS PB5K motherboard may be able to give a more
clear explanation that I.

In any case, do not expect hugh increase in system performance. I use one
EVGA 8800 GTS 320 MByte display adapter. When I use the following settings:
E4300 CPU = 2.7 GHz
Memory = 1200 MHz (DDR2-1200 operation)
compared to
E4300 CPU = 2.7 GHz
Memory = 600 MHz (DDR2-600 operation)
the 3DMark2006 scores vary only a only a few percent.

SiSoft Sandra 2007 has some good low level memory system performance
benchmarks.


Phil Weldon

"Ronny Mandal" <(E-Mail Removed)> wrote in message
news:(E-Mail Removed)...
| Hi!
|
| Got some questions about memory and bandwidth:
|
| I am currently running 4 GB og DDR2 PC8500 Memory modules on ASUS P5K.
| That mainboard natively supports 1333 MHz bus frequency. THe MMs
| supports up to 1066 MHz. But on the POST, the BIOS reports DDR-2 800
| in Dual channel interleaved mode.
|
| I've tried to set the freq. manually to 1066, but then WinXP did not
| start.
|
| Is there a correlation between voltage settings etc. when modifying
| this value?
|
| Hope someome here is able to help me, I do not wanna run my MMs in 266
| MHz less than they're capable of.
|
|
| Regards,
|
| Ronny Mandal


 
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