P4C800-E Deluxe Changing FSB:DDR ratio. Can't do it.

[Jack Markham]

Now that I know how to change the FSB in Manual Mode by using the + and
- keys , I'd like to run my ram a bit closer to 400 MHz by changing
the FSBDR ratio.

My computer appears to be running stable with a FSB of 225. The bios
then sets the FSBDR ratio at 3:2 and my memory slows way down. Is
there a way to change this FSBDR ratio?

Very best regards and thanks for your previous answers to my FSB question.

Jack


Intel P4, 3.2 GHz running at 3.6 GHz
1 gig (2x512) Mushkin 3500 level II running at 300 MHz and 2-2-2-6.

 

[Dan]

If I were you I would have another look at my manual. pg 4-15 explains it.
There is no ratio you select 400 MHz when in manual mode.

 

[Jack Markham]

The options listed on page 4-15 under "DRAM Frequency are 266 MHz, 333
MHz, 400 MHz, and Auto. I do not understand how this answers my question.

 

[Dan]

From your earlier post you are running 1 gig (2x512) Mushkin 3500 level II.
Do you have them in the correct slots as per the manual pg 2-11. If so then
to run them at 400 MHz you select 400 MHz in the BIOS.

 

[Paul]

From your earlier post you are running 1 gig (2x512) Mushkin 3500 level II.
Do you have them in the correct slots as per the manual pg 2-11. If so then
to run them at 400 MHz you select 400 MHz in the BIOS.

The manual has a table like this in it:

CPU FSB DDR DIMM Type Memory Frequency
800 MHz PC3200/PC2700*/PC2100 400/333*/266 MHz
533 MHz PC2700/PC2100 333/266 MHz
400 MHz PC2100 266 MHz

*When using 800MHz CPU FSB, PC2700 DDR DIMMs may run only at
320MHz (not 333MHz) due to chipset limitation.

With a FSB800 processor, there are three available CPU/Memory ratios.
With a FSB533 processor, there are two available CPU/Memory ratios.
It looks like the memory cannot be run faster than the CPU bus.

If you are overclocking by changing the frequency manually, be
aware that the CPU and memory frequencies change at the same time
and their relationship is fixed. The BIOS display doesn't show the
actual memory frequency that results - the memory will be running
at:

CPU_Overclock_Frequency
----------------------- * Memory_Frequency = Resulting_Memory_Frequency
CPU_Nominal_Frequency

For example, with a FSB800 processor running at FSB1000, while the
BIOS display shows the memory at "333", the memory nominal is actually
320, as explained in the table above, and doing the calculation above
gives (1000/800)*320=DDR400 . In that case, the display shows DDR333
while the stick of memory is actually running at its standard DDR400
rate. The BIOS needs a better UI

HTH,
Paul

 

[j0hann0]

This answer i copied from the forums at asusboards (
http://www.abxzone.com/forums/showthread.php?s=&threadid=52328 ) , hope the
writer ( specmike ) does not mind as all credit goes to him ... check the
entire guide out at above link .........

"
I have not seen bios screen shots on other MOBOs but the current Asus boards
are using a bios from American Megatrends Inc. In their bios, you choose a
ratio by either selecting DDR400, DDR333, or DDR266. That is what freq. the
RAM will run at if you choose a FSB of 200. Each speed actually represents a
ratio, DDR400/1:1, DDR333/5:4, and DDR266/3:2. When you change the FSB it
changes the RAM frequency a given amount depending on which option you have
chosen.
"

think this answers yer question

greets Johan