I'll look through fab51 later. This is a lot to take in.
I've been onto the AMD sempron forums and the experts there seem to
think there's no way to lock the PCI/AGP frequencies when increasing
cpu clock from 166MHz with this chipset.
Once you've set the SW1 switch on the mobo off the 100MHz default
setting the bios immediately recognizes the sempron and sets cpu speed
The bios is F7 which was the latest when I last looked a month or so
I don't think using an older bios version is going to help here.
Dave's suggestion seems plausible but I don't feel confident about
I'll add that I've reset the clock to 166 because I wasn't happy with
these frequency variations.
I have some reading to do.
Have a good weekend.
More about :overclocking sempron 2400 kt600 chipset
April 29, 2005 11:48:13 PM
Archived from groups: alt.comp.hardware.overclocking.amd (More info?)
On Fri, 29 Apr 2005 11:02:50 +0100, Stephen Bowden wrote:
> Wes Newell Wrote:
>> On Thu, 28 Apr 2005 11:42:52 +0100, Stephen Bowden wrote:
>> I am still learning this game and I'm learning new stuff daily.
>> Take a look through this.
>> Abit KT7-Raid (KT133) Tbred B core CPU @2400MHz (24x100FSB)
>> My server http://wesnewell.no-ip.com/cpu.php
>> Verizon server http://mysite.verizon.net/res0exft/cpu.htm
> Thanks again Wes
> I'll look through fab51 later. This is a lot to take in.
> I've been onto the AMD sempron forums and the experts there seem to
> think there's no way to lock the PCI/AGP frequencies when increasing
> cpu clock from 166MHz with this chipset.
Correct. But that's not the point. Once you get to a 33MHz boundary, the
divider increases lowering the PCI clock back to normal. So at 100Mhz FSB
the divider is 3. Somewhere on the way to 133MHz the divider will change
to 4, and then 5 going to 166, and then 6 going to 200, and then 7 going
to 233, etc. On some boards you have to change this manually in the
bios. Done right, IMO, it would change midway to the next 33 MHz
boundary.. Done poorly, IMO, it wouldn't change until it reached the mext
33MHZ boundary, but it would still change. I think most VIA based boards
do it the latter way. My SIS based board does it the the first way. The
difference is that at 190MHz my board runs fine using a 6 divider yeilding
a 31.66MHz PCI clock while the latter way would have a 38MHz PCI clock and
likely be too fast for the components to work properly. Basically what
this means to you is that you should avoid all FSB speeds 16 increments
under a boundary. The higher the divider and FSB, the less the effect.
> Once you've set the SW1 switch on the mobo off the 100MHz default
> setting the bios immediately recognizes the sempron and sets cpu speed
> to 166.
The wording for SW1 isn't clear so I don't know for sure which way it
needs to be set, but for a 200MHz FSB it looks like this should be set to
"The system bus frequency can be switched at 100/133/166MHz by
adjusting system switch (SW1). Default Setting: 100MHz You must set SW1
to 100MHz when you used FSB 200MHz CPU."
You must set to 100MHz when using 200MHz cpu?:-)
You have to try both settings I guess.
> The bios is F7 which was the latest when I last looked a month or so
> I don't think using an older bios version is going to help here.
Maybe, maybe not.