Archived from groups: alt.comp.periphs.mainboard.asus (
More info?)
Hi there, actually the motherboard is using the Intel 815 chipset. I was under the assumption that the RAM speed and
motherboard FSB had to be the same. But, I see motherboard/cpu combos all the time on ebay where the cpu is 133 FSB and the
ram that comes with it is PC100. Normally I would just make sure the speed is the same, but as I said Im trying to fix my
friends computer at minimal costs, and if her current PC100 SDRAM will work with a cpu that has 133mhz FSB, (intel 815
chipset) then that is fine by me. So is it possible on the i815?
On Fri, 01 Apr 2005 14:45:00 -0500, nospam@needed.com (Paul) wrote:
>In article <1b4r41hf8vd8nn9itlii9lr33som3c1ms1@4ax.com>,
>flesh@*no*spam*.tconl.com wrote:
>
>> Sorry for the stupid question, but I am trying to fix a
>> friends computer. I need to replace the motherboard and cpu.
>> My friend currently has 512mb of PC100 SDRAM. I found a
>> motherboard/CPU combo on ebay thats inexpensive, BUT.. I'm
>> not sure it will work with her ram. The cpu in the combo I
>> found runs with a FSB of 133 (its a p3 933mhz). Will my
>> friends current 100mhz RAM work with the new 133mhz FSB cpu?
>
>As far as I know, memory and FSB are operated at 1:1 only. That
>is, if the board you are buying uses the 440BX Intel chipset.
>
>http://homepage.hispeed.ch/rscheidegger/p2b_procupgrade_faq.html
>http://homepage.hispeed.ch/rscheidegger/ram_bx_faq.html
>
>One option would be to slow the processor down, from 933 to 700,
>by using any DIP switches placed on the board for such mods.
>You can then play with the clock and test whether the RAM is
>still stable or not.
>
>With the 440BX, there is an AGP divider that is set to either
>1/1 or 2/3. At 133MHz, AGP runs out of spec at 89MHz. At
>100Mhz, AGP runs in spec at 66MHz. At FSB 66MHz, the 1/1 setting
>should be selected by the user, to get AGP running in spec at
>66MHz. The 89MHz seems to be accomodated by most old video cards,
>so this should not be a limitation.
>
>As for PCI bus speed, there are a couple of possibilities.
>Some clock generators have a 1/4 divider that operates at
>133MHz, and that gives standard 33MHz PCI bus operation.
>There are also some that only have 1/3 divider, leaving the
>PCI bus at a non-stanaard and non-working 44MHz.
>
>I'm guessing this motherboard was designed to run 133Mhz
>processors, in which case if the 440BX chipset is used,
>the AGP runs at 89MHz, and that should be OK. Dialing down
>the clock that feeds the processor, should allow you to
>run with the PC100 RAM. Make sure the motherboard has
>adjustments, such as the DIP switches mentioned above.
>
>Take a look at page 18 here, to see what an adjustable
>motherboard looks like:
>http://www.asus.com/pub/ASUS/mb/slot1/440bx/p3b-f/p3bf-104.pdf
>
>For more precise info, posting the motherboard brand and model
>number might be a good idea. It is possible, if some other
>chipset is on your new motherboard, that other things are
>possible. The 440BX just happens to be the "king of stability".
>I have a board with 440BX and it still works.
>
>HTH,
> Paul
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