Weird FSB changes

So, my 2.4C has been sitting at 3 GHz for about 5 months now, with no problems. My Corsair PC3200 is at DDR400 at 5:4.

Two days ago I changed my AGP aperture from 64MB to 256MB. I beleive this is the only BIOS or other configuration change I have made to the system, except for switching antialiasing and anisotropic filtering on and off constantly - but I always do that.

Today I realized that my 2.4C was running at 1500 MHz. I used CPU-Z to confirm; my FSB was at 125 MHz, and my memory was at 100 MHz, despite the fact that the FSB was set at 250 in th BIOS, and the memory ratio was at 5:4. Restoring the BIOS defaults did not fix the problem - as soon as I changed the FSB back to 250, the system would boot at 1.5 GHz.

Clearing the CMOS and putting everything back to where it used to be fixed the problem, and now I am running at 3 GHz again. If I change the AGP aperture back to 256MB, the FSB drops again. What's going on?

you put an agp aperture of 256 with a ti4200 128mb.
Notice a pattern?

Stranger than fiction. Which bios? Happens at 250fsb only/exactly?

Ritalin said:

you put an agp aperture of 256 with a ti4200 128mb.
Notice a pattern?

Click to expand...

The AGP aperture sets the amount of system memory that is addressable by the video card. There should be no problem setting it above the memory capacity onboard the card.

Grandpa Dan said:

Stranger than fiction. Which bios? Happens at 250fsb only/exactly?

Click to expand...

Yes very strange. Stranger still, because when I went to check if other FSB settings cause FSB changes with a 256 MB AGP aperture setting, I found that now 250 FSB and a 256 MB AGP aperture works fine... Maybe it has something to do with a certain number of reboots and settings not sticking in the BIOS? I'm using 1010.

I've never seen BIOS settings change, but still be reported as normal in the BIOS (i.e. the system was at 125 FSB, but the BIOS said 250 each time I rebooted).

maybe you should upgrade your BIOS... revision 1012 is out... it might work up those weird fsb changes...

Maybe...

Things seem to be fine, now, and tomorrow I'm leaving school for Xmas break, and this thing will be shut down for three weeks.

I'll keep a BIOS flash in mind.