noob fsb quest - reduce sonoma heat by lowering the fsb freq

[nrj45]

If speedstep is able to change the cpu frequency "on the fly", how about the fsb ? Is it that hard to have a "mobile fsb" ?
Because if the fsb was also underclocked in idle mode, it would allow a lot more flexibility to t43/p models no ? I mean idle : cpu 800MHz, fsb 200MHz.
Because if the cpu is idling, it doesn't need to have a 533MHz fsb.

This would make the chipsets cooler, autonomy better, less heat,...

[Kel Ghu]

Heya,

The CPU-to-PCI bridge is actually 133Mhz, but the system bus is quad pumped, 4x133Mhz = 533Mhz.

Dont know about the us multiplicator, but the should be a way to change the FSB to 100Mhz (400Mhz) and lower.

[nrj45]

That was what i thought (50Mhz fsb, quad pumped --> 200)... but speedstep and CHC act only on the cpu multiplier and not on the fsb itself...

[Kel Ghu]

this may be the way to lower the chipset temperature and shutting the fan off. Really!

I've found several website et program that would allow us to lower the FSB of our laptop. Though there's one thing we must find is the PLL the chipset uses, meaning we have to open our laptop to find it. If we know it, we simply have to use some simple program to change it.


Here's some link to those program:
http://www.cpufsb.de/index.html
http://www13.plala.or.jp/setfsb/

And if people want to understand how it works, here's a link to ars technica:
http://arstechnica.com/cpu/2q99/bxhack/ ... -bx-1.html
It's old but it basically works the same way.

And a very interesting link, but in french (I know you can read it nrj45):
http://forum.hardware.fr/hardwarefr/Min ... 5943-1.htm

I'll look at the picture ppl did for the south bridge cooling... Maybe Ill find the PLL..

[Kel Ghu]

I tried to find the PLL for our T43/p on the pictures but no way I could read chips ID. And i'm too lazy to open my laptop. nrj are you willing to do it? Or anyone else?

[Kel Ghu]

Oh yeah, the chips looks like this:
http://www.cpufsb.de/FSB.HTM

[fbrdphreak]

Hey guys,

First off, I don't know of any software that will let you change the FSB on any 915 chipset (T43's) and the 855PM (T40-T42 w/discrete graphics) usually doesn't work either. It is generally only the 855GM/GME (integrated graphics) that has FSB software support.

Also, in regards to a "mobile" FSB: it is theoretically possible. The issue I think is with changing the FSB clock you introduce a lot of potential for instability. I would imagine it becomes so complex to synchronize everything that it ends up being more hassle than it is worth. Also, the Intel Pentium M chipsets to power down parts of the FSB circuitry when not in use, versus lowering the clock.

Right now power saving technologies (like Intel Enhanced SpeedStep) work by reducing the CPU multiplier and voltage; a lower multiplier reduces clock speed, allowing the notebook to run at a lower voltage (less voltage is needed to run a chip at lower clocks).

The FSB on Sonoma notebook is a 133MHz internal clock, but Intel samples the bus FOUR times per clock cycle. This allows for an effective clock speed of 533MHz (133*4).

[Kel Ghu]

Well, look at my links and you'll find programs that change it for 915 chipset and 855 too.

I dont see any problem in lowering the clock. All the components sync on the bus speed. Of course there may be instability if the speed is too low, but it should be OK. Computers are more underclocking friendly than overclocking. And mobile chipset are not very different from desktop chipset besides power managing features which are not very bus dependant. So I dont see any danger in doing this except damaging the PLL (phase-loc loop), but it could happen with desktop computers too.

And you miss the point in why we want this... We want to lower the temperature while in use. Power saving comes second. Speedsteps and power management technologies only provide micropower management, meaning it tries to save energy while the energy is not needed . We need macropower way to be able to reduce temperature while in use, meaning speedstep is of only little use here. We have no other choice that have drastic solution to get what we want. We want the fan to shut down.

[fbrdphreak]

I don't think lowering the FSB itself will cause problems, I was referring to a dynamically changing FSB

I had talked to some people who were looking for 855PM/915 FSB utilities and they said they hadn't found any. If these work, great

If you lower the FSB to 100MHz, you'll be back to the Dothan's original 21W TDP that the T42's were designed for.

Worth a shot I guess

[nrj45]

It's exactly the debate such a topic should initiate.

My question was just the result of a "personal brainstorming".

So now, we can discuss :
- whether it's possible or not
- whether we can change it "dynamically" according to the load or not

Personally, the must would be to be able to "tune" the fsb accordingly to the job i want my t43p to do. I want my t43p to be the more flexible possible.

Thanks for interest and I wish us good luck in this "new" way of "cold seeking".

NB : I changed a little the title of this thread...

[fbrdphreak]

One thing I should clarify is that out of the box, no software will dynamically adjust the FSB.

If you were to write an app that varied the settings in the FSB software, I think that's just asking for a crash. Dynamically sending commands down from the OS to the hardware layer and expecting everything to work smoothly is just crazy

Maybe instead you should climb up Lenovo's butt and get this situation rectified from them; its a substandard cooling problem in all reality

[Kel Ghu]

One thing I should clarify is that out of the box, no software will dynamically adjust the FSB.

Disagree... Such programs exist since intel BX chipset (7-8 years ago), program such as softFSB. I gave links to those program...

Dynamically change the FSB can be dangerous, as we will have to access to the PLL which can damage it. If we have access to it, we can dynamically change de FSB from windows without any problem, but we have to know what PLL we have in there. Dynamically changing the FSB is the only way to change the FSB speed as there's no options in the bios and i doubt IBM will give us such options.

But fbrdphreak is right when he say it can be less stable to change it dynamically.

[fbrdphreak]

I don't mean that you can't change the FSB to whatever you want. This is very common on desktop chipsets: there is plenty of software to change the FSB on the fly to whatever you want in Windows. This is typically less reliable than doing so in the BIOS, but it is prefectly fine.

What I mean is that there is no software that will adjust the FSB based on CPU load. Right now the P-M gets such excellent performance & batt life because the CPU clock is varied based on CPU load & a few other factors. You would have to write your own software to control the software that manages the FSB speed, and have it change the FSB speed based on CPU load. This is not impossible - just incredibly tricky and with one program managing another program that manages the FSB through a hardware abstraction layer, you're asking for trouble.

If you want to do something PRODUCTIVE towards reducing the heat on your T43's, check out the Battery Optimization Guides here:
http://www.laptoplogic.com/resources/guides/

[Kel Ghu]

oh yeah ok. sorry was misunderstanding.

Yeah, ure right, difficult to dynamic FSB change. Easier to change CPU multi as only the cpu has to resync.

[nrj45]

By removing keyboard (don't have time to open completely my t43p) i didn't see anything like on pics. I tried to remove the internal ram and i saw some chips i don't know if they are plls. I saw these numbers on :

P15c
16862cb

Question : if we could "tune" the fsb would it be the same as for the cpu ? fixing a voltage and a frequency ?

I'm completely novice in this topic... If we underclock/volt the fsb, what about pci and pci express frequency ?

Another thing : How about CHC ? If we want to sometimes boot with a 100Mhz fsb and sometimes with a 133MHz fsb, we have to change all voltages for each multiplier no ?

[nrj45]

I reinspected my t43p without finding anything looking like a PLL. Is it possible that it is on the other side of the mobo ?

[Kel Ghu]

everything is possible... But it is very unlikely it is on the other side... Wierd...

[ddutta]

Is it possible to find a SW utility to change teh FSB speeds. My friend has a Athlon64 and his Gigabyte overclocking utility can easily do that

[Kel Ghu]

it's because the prog is made for his motherboard, meaning the prog know the PLL.

[Rhino]

NRJ, as soon as my new Tpad gets here I will help you with this! )

[nrj45]

Thanks .

[ruthlessbrad]

I also found nothing like a crystal or PLL. I removed the keyboard, palmrest, and the wireless card. I had my heatsink off earlier today, but I forgot to look. It might be under the heatsink, unless someone else has taken it off and verified it isn't there.

[mistiko]

I'm also interested in finding t43's PLL, I've tried many progs but without success Unlike my TOSHIBA M2 (centrino 1.6@2.0 GHz) the T43 seems difficult to oveclock, at leats without knowing the right PLL!

[agarza]

Reviving this topic a little, I search for the FRU:
BM ThinkPad T43 Laptop HeatSink FAN 26R8197
http://i6.ebayimg.com/03/i/08/29/89/ca_1_b.JPG

Indeed it covers the northbridge I didn't such a heatsink would exist. IBM should've shipped all T43 (maybe T42) with that FRU

My T41p fan short was replaced for the FRU 26R9074, I wonder if the original T41/T42 fans run more quietly when spinning.

Also, after 1 year, I would like to know, now that we have TP Fan Control, what's the laptop temperature readings after modding with the copper plates.