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-   -   Use an P4 Intel M SL725 on a desktop (http://www.hardwarecanucks.com/forum/cpus-motherboards/404-use-p4-intel-m-sl725-desktop.html)

lamimartin February 21, 2007 08:43 AM

Use an P4 Intel M SL725 on a desktop
I am thinking of using a Pentium 4 Mobile on a ECC desktop motherboard that uses a
865G (GMCH) chipset. The only problem with specs is matching the CORE VOLTAGE, Intel is telling me 1.3 volt and CPU World Website specifies this M type P4 can work with a core voltage between 1.2 to 1.525V. I wish intel were more specific ! There is no confirmation ont their website whatsoever about core voltage range for that processor.

As far as I know, a desktop motherboard will detect the appropriate core voltage up to 1.525V. In such case, I am understanding it would run at 79.38C wich is within its thermal specification.


Thank you (see specs below)


Here are the specs I found on CPU World Website:

V core (V) 1.475 - 1.525
Min/Max operating temperature (C) 5 - 75
Min/Max power dissipation (W) 76.58 (1.475V) 77.98 (1.5V) 34.06 (Stop Grant mode) / 79.38 (1.525V)
Processor frequency is reduced to 1.6 GHz in battery-optimized mode (1.2V)

Babrbarossa February 21, 2007 09:20 AM

Hi! Welcome to the forum! There are some real experts here, but unfortunately, I'm not one of them-- but I'm sure someone here will be able to answer those questions-

I probably wouldn't worry about heat too much as the desktop environment will be much cooler than in laptops.

Here's a little article on using laptop cpu's in desktops- not extremely helpful... link
And here's a short thread on the p4-m in desktops-
And another thread on p4-m's in a desktop (someone says make sure to disable speedstep to avoid downclocking)
Another short thread (not as helpful)

Which processor is it exactly? The 1.3V sounds more reasonable than the 1.525- I wouldn't give it that much. Is it a Banias, or a Dothan? (Nevermind ragz, I see now that it's a Northwood)

865GSpringdale82865G (GMCH)ICH5/ICH5RMay 2003Pentium 4400/533/800 MHzNoDDR 266/333

lamimartin February 21, 2007 10:01 AM

Ist question answer is in the title: P4 Intel M SL725

Thanks for your threads. I'm surprised to hear about a 479 pin for Pentium M !!?? This extra pin It is not mentionned on Intel or other vendor's websites. This mysterious adaptor from Asus would prevent me from using a standard CPU fan and clip. I don't like the idea.

If the SL725 has indeed 478 pin, I think I can control the voltage using the BIOS to force it to go at 2.8 GHz, as the other thread suggests. I only want to be sure before I risk frying the CPU or the Motherboard.

Babrbarossa February 21, 2007 10:30 AM

The adaptor is for the dothan, not the northwood -so it's not for you anyway

Misoprostol February 21, 2007 07:27 PM


there are only a couple of desktop boards that support Pentium M processors. Pentium M uses S479. It is physically different from a desktop P4 CPU, and will NOT FIT in a desktop board without using an Asus adapter on an approved Asus motherboard.

Post the exact model numbers of the motherboard and CPU and we can let you know if it will work. Otherwise you will likely end up ruining something...

Babrbarossa February 21, 2007 07:59 PM

Speaking of models, I see you've discovered that your quad is a zeon ;-) (got the cpu-z update i guess)

lamimartin February 21, 2007 10:27 PM

Thank you, it definitely answers my question. I did not know there was different flavors of 478 socket so that it would not fit without an adaptor. I won't even bother to try and return the used P4M CPU to the vendor (that offers a refund, minus shipping).

Babrbarossa February 22, 2007 04:00 AM

There is a difference between a pentium-m (dothian, banias) and a pentium 4-m (northwood)

It seems that this is a northwood cpu that fits 478, not like the petium m dothan and banias that fit 479- -check out these links- Notice in the top one that there are no northwoods in the 479 sockets-- this cpu is 478.



Here's his cpu-z info: (got it from the NCIX forum where I assume it was lamimartin that posted the same kind of question under the name ragz.)
Intel P4 (512KB L2)
Northwood (8)
478mPGA (0.13um) And here is the chipset
Mobile Intel(R) P4 2.46Ghz
Family F (Ext. F), Model 2 )Ext. 2), Stepping 9, Rev 01

lamimartin February 22, 2007 08:00 AM

Mystery solved, but theory not proven to work.
Thanks Barbarosa, You don't give up !
Interesting... :thumb:

The link I found on the Wikipedia page you quote about Pentium M is pointing on http://processorfinder.intel.com/List.aspx?ProcFam=942 is listing A FEW 1.6 to 2.10 MHz that has the 479 pin package instead of 478. But it is NOT talking of P4 M.

As you understood, the Pentium 4 M processor I ordered by mistake is a P4 M SL725 2.8 MHz which is not listed on the links you mentionned, because it is a Northwood. I only found ONE Northwood with the Pentium 4M listing at Intel that has 479 pins. All others are 478 pins. The following link is more relevant to my problem:

The entry that matches my processor is listed under Nortwood 130 nm Intel OEM Part number RK80532GE072512.Mobile Pentium 4 2.82800 MHz, 512 K, 1.2/1.55 V /Socket 478. The intel part number matches the SL725 page on their website that only mentions 1.3 volts as core voltage. I can't wait to read the voltage info on the processor itself ! Finding a mistake on Intel website about such critical information would be quite disturbing !

So, if core voltage is indeed 1.2-1.55 volts, not just 1.3 volts, I think it DOES fit into my socket 478 desktop motherboard without adaptor and it DOES work without frying anything. The whole idea is to find a way to control the core voltage by forcing it to run at 2.8 GHz, not slower, in the BIOS. So I think the first links you pointed out are suggesting this is the only problem that I must experiment to prove it can be done. I suspect that some motherboard will not provide more than 1.5 volts and the 2.8 GHz processor will run at something like 2.6.

In short, I think there are some RARE cases of Nortwood and Nortwood HT Pentium 4 M that fit into a 478 socket and can safely work at 1.5 volts. The SL725 is one of them. The whole question is to find a motherboard and BIOS that will allow it to run at full speed (and HT or bus speed compatible).

By the way, I'm not "Rags":bleh: I'm a former computer consultant and hardware specialist with 13 years of experience. My first PC was an XT with twin floppies, PC DOS and Wordperfect 2.1... in 1985. It remains a hobby for me.

Otherwise, I would not bother to assemble parts from Ebay to make my home computers. For the price of ONE new computer, I upgraded two of my computers to P4 2.66 and still had enough spare parts to assemble a PIII 1GHz, all with 1GB of RAM and plenty of HD space.

I appreciate you take time to READ and really look for answers. This is RARE. You should just see the full page of silly information I received from ASUS. The guy did not even try to answer the question. I was submerged into useless basic info.

Im not 100% sure I will perform this experiment or simply return the P4M processor, loosing delivery and return shipping cost. At least I now have reasonnable grounds to beleive it is worth trying it without frying it ! :rofl:

Thanks again for your kind advises. It is appreciated


Babrbarossa February 22, 2007 08:13 AM

Sorry for assuming you were "rags"-- It just seemed too much of a coincidence that someone was asking the same question about the same kind of cpu, on the same day on another forum.

Your welcome for the help- sorry for not really being able to help (I'm still a noob)-but when someone asks a question that I can't answer, curiosity impels me to look into it.

I don't know if you noticed the comment that I wrote about disabling speedstep in the bios to make sure that the cpu runs at full speed- might not work for you...

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