SoftFSB / CPUFSB Question....

[X-Caliber]

Hi,

I was wondering, if I boot my PC with a 100MHZ FSB, and then use either SoftFSB or CPUFSB to change to 133MHZ FSB, will my processor speed change? My processors have a 10.5x multiplier, and do run at 133MHZ. Is it safe (will I harm my processor) if I dynamically raise the clock speed like this?

Out of curosity, I tried this (setting the FSB to 133MHZ, from 100MHZ) and then ran Sandra. But there was no change in the benchmarks, which means the processor speed did not change. So either this can't be done, or I am doing something wrong.

Please give me your thoughts.

-V-

[Admiral]

What CPUs, what motherboard and can't you raise the fsb via bios ?

[X-Caliber]

Dual 1.4GHZ Tualatins (133MHZ * 10.5) on an ASUS P2B-DS REV 1.06 D03 motherboard (which supports a 133MHZ FSB); but the FSB cannot be changed via BIOS. I can set the FSB with the jumpers on the board, but for some reason my Matrox Rainbow Runner G series card does not work at 133MHZ with the Tualatins. BUT, when I use my two 800MHZ CPUs, also @ 133MHZ FSB, it works fine. So I have had to downclock my two Tualatins to 100MHZ, to get my RRG to work properly. Anyway, when I boot up at 100MHZ (w/ the Tualatins), and switch to 133MHZ, the RRG still works, but I don't think the CPUs are running at full speed. annoying

[Jon P. Inghram]

You might want to check this site: http://tipperlinne.com/p2bmod

[X-Caliber]

yeah I've been there. It's pretty useful, but doesn't answer my question

[Admiral]

Reading through Jon's link, seems your PCI bus doesn't get reseted at 133 fsb and you're stuck with 44MHz PCI that isn't good for your RRG.
Adding the FS3 jumper there seems to fix it and allow you to reset it to 33MHz.

[X-Caliber]

yeah, I know. But believe it or not, most cards don't really care if the PCI bus runs @ 44MHZ!! In fact, when I used my dual 800MHZ EBs, I left the PCI bus @ 44MHZ w/ the FSB @ 133MHZ, and everything worked fine (including the RRG). But when I swapped the 800MHZ for the Tualatins, the RRG wouldn't work @ 133MHZ anymore.

[Wombat]

Originally posted by X-Caliber
yeah, I know. But believe it or not, most cards don't really care if the PCI bus runs @ 44MHZ!! In fact, when I used my dual 800MHZ EBs, I left the PCI bus @ 44MHZ w/ the FSB @ 133MHZ, and everything worked fine (including the RRG).

Hey, it's your gamble. But personally, I wouldn't do that to my components, especially my hard drives.

[bsdgeek]

Yeah, the high PCI Bus will probably cause some data corruption. It's the main problem I run into during my (somewhat limited) overclocking escapades.

[X-Caliber]

Usually I just use SoftFSB and change the 133/44 to 133/33. My firewire webcam shows a difference right away; @ 44MHZ, there are lines all over the image, but @ 33MHZ, the lines dissappear. Not really an issue! Btw, the RRG runs fine @ 44MHZ, but I usually run it @ 33MHZ anyway. As for my hard drive, my motherboard has a built-in SCSI controller, with a fixed 40MHZ bus, independent of the PCI bus speed!!!

btw, anyone know how to answer my question?

-V-

[Admiral]

Use WCPUID or CPU-Z to check if the CPU clock changed.

[X-Caliber]

Thanks for the link. WHen I change the FSB, CPU-Z says the processor speed has changed too. But when I run Sandra, I get the same benchmark scores (???) Is there another benchmark program you could recommend?

WAIT!! WCPUID does not show any changes in either the FSB or clock speed??? So CPU-Z shows a change in both the FSB and internal clock speed, but WCPUID shows no change. Furthermore, when I run SoftFSB, it says that the FSB is 133MHZ, but it shows NO change in the internal clock speed.

strange!

[Admiral]

Thanks for the link

Sorry 'bout that

Is there another benchmark program you could recommend

Well, Quake 3 should show a small increase, mainly from the memory bandwidth increase I guess and partially from the CPU.
The UT2003 botmatch result from the benchmark should increase, this one's CPU bound.

You could also try 3Dmark 2001SE or PCmark 2002.
(Futuremark downloads )