Underclocking a P4 2.4C

zavier · Post by **zavier** » Sun Oct 24, 2004 2:12 pm

I'm looking for a way to underclock a P4 2.4C by running the FSB at 133MHz, which would run the processor at 1.6Ghz... Is there a way to bridge some pins? My motherboard is from Intel and has no tweaking abilities...

Thanks!

Post by **Ralf Hutter** » Mon Oct 25, 2004 5:03 am

You'll find that your CPU doesn't run much cooler if you underclock it because it still uses the same voltage as when it was running at full speed. What really helps lower your CPU temps is the undervolt the CPU while keeping it at it's default speed. Of course your Intel board can't do that either....

I know you can futz around with the pins to fool the mobo into thinking it's running a chip with a different FSB, but I've never heard of anyone trying to downclock their FSB and am not sure where, if anywhere, you could find info about that.

Most people want to overclock their CPUs so any info that shows up is about doing that. Maybe you could look around on some of the OCing sites (OCforums.com , hardocp.com , etc) to see if there's pin tweaking diagrams that you could reverse-engineer.

mczak · Post by **mczak** » Mon Oct 25, 2004 10:51 am

Tricking the board to lower FSB shouldn't be too difficult in theory, look at the P4 datasheet and watch out for the BSEL pins. As Ralf said, it should work just the same as if you try to increase FSB.
You can also lower voltage that way, which was already said to be much more effective, watch out for the VID pins.
Though it might be tricky in practice, last time I pin-modded a cpu (a tualatin to get it to work with a non-tualatin s370-slot1 adapter) I had some problems with isolating pins & connecting others (with that silver paint stuff), since everything is so tiny...

Post by **Ralf Hutter** » Mon Oct 25, 2004 4:28 pm

mczak wrote:I had some problems with isolating pins & connecting others (with that silver paint stuff), since everything is so tiny...

And it's even tinyer with Socket 478 systems. I pin-modded a couple of S370 CPUs back in the day, but I'd be too scared to try it with S478 stuff.

zavier · Post by **zavier** » Mon Oct 25, 2004 8:45 pm

Thanks for the replies.

I guess I'll leave the clock and voltage just as it is for the moment...

I'm mostly interested in lowering the power consuption during idle, since I'm using that computer for trivial tasks (CPU wise), so I'm going to look for a motherboard with voltage regulation in the BIOS.

peacefulpc · Post by **peacefulpc** » Mon Oct 25, 2004 10:46 pm

also, take a look at this recent article:
http://www20.tomshardware.com/motherboa ... index.html

they say that you can overclock a p4 with a new 915/925 asus board. of course they don't discuss underclocking/undervolting, but more control is a good thing, and could be promising.

of course, that doesn't help your situation

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