S478 P4 M(non Dothan) compatibility w/ desktop MBs

[OC4fun]

Trying to decide on a good OCable build and was leaning towards the notebook applications for use in my desktop. I have looked at S478 b/c these are affordable and in my price range for my first OC build. I would like to know what would be the limiting factors for attempting to use a P4 M 518(2.8 533 fsb) in my I875P MB. If incompatible with a certain desktop chipset, what would be a viable solution for use of such cpu? My plan is to use the cpu with existing hardware and not have to OC dram clock in an attemp to use the high multiplier of 21x133 to achieve something like 21x200 making this a 4.2 with HT and 1MB cache. I have high hopes, but doesn't this seem like a dream, and is probably not capable. I would like to know if anyone has tried such or if it would be possible, and if not, plz define the reasons why and suggest an alternative. ty

[Lancelot]

I don't think you can use a P4-M cuz it has advanced speedtstep capabilites and I don't think your mobo supports the ultra low Vcore needed. Maybe u can use a Mobile-P4 cuz these seem to use a regular Socket478. (yes, you have 'P4-M' and 'Mobile-P4')

[OC4fun]

Yes, I was refering to the mobile-P4 518 2.8 socket 478 not the socket 479 Dothan. I have read the specs and it appears it runs at normal vcore of 1.5v full speed. Why would the centrino(Dothan) work with an adapter and this particular cpu not is what I need to know or if it would I need this info before purchasing a $200 piece of hw ty

[Reefa_Madness]

Unfortunately, the problem lies in the multiplier. When used on the desktop, these s478 Mobile Pentium 4s default to the lowest multi in the lineup, in this case being 12, not the 21 that you've shown above. SpeedStep compatibility is the feature that is missing from desktop BIOS and what causes us the grief.

You have in effect the equivalent of a 2.4 when you run at 200fsb, not 4.2 as you hoped. Below are some links that will support this. There is a tiny ray of hope that I am pursuing myself (I have a 3.2 and bought it under the impression, like you, that I would be able to use the default multi and achieve high clocks) and this is a Russian s/w that is supposed to be allow you to change the multi from within Windows. I have not been able to do anything beyond a download due to time constraints. If you get anywhere with this I would certainly appreciate hearing from you.

Good luck (for both of us). Now you don't have to wonder what you are going to do with your spare time...you'll be chasing links down for the next week or so. :)

Link to the Russian software...it briefly came up in a Silent PC Review article. They indicated it worked, but had issues. To me, this is our best hope and what I will be concentrating on myself, when time permits.

http://cpu.rightmark.org/products/rmclock.shtml

This is the article that mentions the above linked software.
http://www.silentpcreview.com/article218-page9.html

Link to site on Mobile P4 and discussions on the multi issue

This one is on overclocking the 400 fsb version (you and I have the 533 fsb):
http://www.vr-zone.com/guides/Intel/P4M/

Other related links, in no particular order:

http://www.xtremesystems.org/forums/showthread.php?t=47909&highlight=desktop+mobile+533FSB

http://will.dashwood.me.uk/pentium4m.htm

http://www.bay-wolf.com/speedstep.htm

http://forums.silentpcreview.com/viewtopic.php?t=12983&highlight=guide

http://www.diefer.de/speedswitchxp/index.html

http://www.xtremesystems.org/forums/showthread.php?t=39193

http://www.xtremesystems.org/forums/showthread.php?t=42033&page=2&pp=25&highlight=Asus+multiplier+unlock

Intel - SpeedStep Features and stuff

http://developer.intel.com/design/mobile/mp4p/documentation.htm

http://www.intel.com/cd/channel/reseller/asmo-na/eng/203838.htm#Desktop_System_Requirments

[Reefa_Madness]

Yes, I was refering to the mobile-P4 518 2.8 socket 478 not the socket 479 Dothan. I have read the specs and it appears it runs at normal vcore of 1.5v full speed. Why would the centrino(Dothan) work with an adapter and this particular cpu not is what I need to know or if it would I need this info before purchasing a $200 piece of hw ty

Forgot to address this.

The Dothan and this Mobile P4 are two different animals and have nothing to do with each other with respect to use on the desktop. The adapter is required (I'm pursuing this toy myself, but not related to the Mobile P4) in order to allow the Dothan to operate on an 865/875 Asus desktop motherboard. It will only work on Asus boards that have updated the BIOS to be compatible. The mobile P4 will work on most branded mobos as a regular P4 does, but with the (big) multi issue that I mentioned in my first post.

Hopes this help...bottom line is the CT-479 adapter is not needed, nor applicable, to your situation.

[OC4fun]

Well that looks like a challenge :( which the board/BIOS manufactures can easily fix. I like how ASUS develops an adapter for the Dothan's! but nobody adds code in the bios' for the speedstepping support. I was gonna go with a 2.8A 533 fsb 1MB L2 before I thought of the notebook cpu, I think I may just try out my first choice and leave the mobile P4 alone. I could still reach 4.2 on this particular cpu but would require heavy duty cooling and does not feature HT like the mobile does :-/. Tyvm for the links/info and maybe in the future when I have more time/money I can venture into working on such a project.

[Reefa_Madness]

Darn! I was hoping you would have done the legwork for me.

Just kidding. I certainly understand why you would not venture this way. I have a mobo that will do 300, so in the worst case, I can run it at 3.6GHZ (12x300), which I guess isn't all that bad. It should do so at lower temps than a normal P4, which is a good thing.

[Ssetre]

Abit AI7 + P4M boot strap set to 200fsb. Stay away from DFI!! I had to pin mod on their supposed overclocking friendly board. There tech support is full of *beeping* *beeps*.

Dfi's are bad as they lock all previous gen chips to one fsb below the next step. I could only get 132fsb and after that it was locked. Oh and the volts were drooping really bad on it. I used a 865PE Infinity.

My abit has a problem though it seems that it won't let me go past 245fsb. At 250 it starts acting funky and I am still at stock volts :(. But the abit does support the P4M microcode so that helps but make sure you go in and change the bootstrap to 166 or 200. Also make sure of the stepping of your cpu. At 2.92(rock stable) my p4-m hands a Athlon XP at 2.57ghz its butt in 3dmark03 :).

Also later mobiles like this revert to a 16x multi not the 12x of older mobiles.

[Reefa_Madness]

Also later mobiles like this revert to a 16x multi not the 12x of older mobiles.



Which cpu do you have with a default multi of 16? Everything that I've read and seen so far has indicated a 12, but in truth, most of that info, with the exception of one forum thread which specifically addressed the 3.2 (and that thread could have been in error), has been on the 400 fsb version, not the 533.

Would you mind providing the codes of the cpu (if you have them written somewhere (or on the original box if bought retail). If I could get a multi of 16 I would be set!

[Ssetre]

D1 and later core mobiles use a 16x multi to drop down to.

I've long since forgotten the Sspec on mine. But its a Pentium 4 Mobile 2.0/512K/400. It drops to a 12x multi when in a desktop from the original 20. Its a C1 stepping, almost all 533fsb Mobiles are D1 and later.

[spyrollinc]

my a75 3.2 has a 538 e0 revision. it defaults to a 14 multi on battery power. but if i use cpumsr i can set it anywhere from 14-24.

[Ssetre]

I hate the fact my cpu only has speed step and not the enhanced one. I can read the available multi's but I can't touch em.