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PCI speed on 133DDR Bus

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Stolid

Member
Joined
Jan 7, 2001
I was reading through my Abit manual and noticed that it mentioned my PCI speed changed with my FSB (naturally - I knew this) - but it did not mention a way to change the fraction and actually gave a list of FSB/PCI comparisons - The board is the Abit-KT7a-RAID meaning it's designed for the 133 BUS but won't running at that speed (40-some odd MHz PCI IIRC) be overclocking my PCI cards before I even begin real overclocking? I didn't notice a fraction change anywhere in the manual (albiet I have yet to get my processor). Now, I also was curious about the FSB-CPU or somesuch setting below the PCIspeed in Softmenu - what is this? Is it the old async-feature of running your 133 MHz RAM at 133 while your proc/FSB was only 100 but for the CPU? Thanks in advance!

Stolid
Who will have to borrow a friend's CPU fan to boot this for the first time. :p
 
N

Nomis

Guest
you can use CPU FSB/PCI CLOCK to keep the PCI bus speed low and use CPU FSB PLUS (MHZ) to change the fsb increase form 1MHz to 28MHz. A great feature.
So,
CPU FSB/PCI CLOCK CPU FSB PLUS (MHZ)
100/33MHz, upto +28,128/33MHz
103/34MHz +28,131/34MHz
105/35MHz +28,133/35MHz
110/36MHz +23,133/36MHz
much better than,
133/44MHz +0, 133/44MHz

Hope you get the idea!
 

goman

Registered
Joined
Feb 8, 2001
Location
Ohio
Do not quote me but If that board has the VIA 133A chip set the PCI and AGP multipliers are automaticly adjusted when you pass 120 on 100mhz and 153 on 133 mhz FSB I am sure it is automatic but I am not sure if the 120 and 153 are exact. Do not believe sisoft SANDRA she dosn't understand the 133 (A ) chip set.
 
N

Nomis

Guest
This is a new feature replaced the 1/4 PCI setting in softmenu III. According to the Abit manual at 120MHz, it will be 40 MHz PCI, That kinda high, so instead, use a lower fsb with a lower PCI and use the CPU FSB Plus (MHz) feature to get the same speed but with a lower PCI bus speed. For speed above 133MHz/44MHz, at 136/34MHz the 1/4PCI kicks in. and the PCI only go up to 38MHz at 155MHz fsb.

The IwilI is different than the Abit, I have no idea about what the KK266 PCI bus speed is, all I know is the 1/4 PCI in set auto and I have no problem with any pci card when o/c up to 161MHz fsb.