CPU substitution - 400Mhz FSB ppga478 compatible with other 400Mhz FSB ppga478

[lvlenovo]

I have decide to have some fun with modifying my A31.

Although it may not really be worth the increase in performance, fan running time may be dropped. For 10$ it may be worth a try.

I am thinking replacing a P 4M with a Pentium M(Banias or Dothan). For the models that I am looking at, according to the Intel site, the FSB match the original 400MHz, however the cache is larger ( up to 2MB from the original of 512kb).

Would this be possible or would the cache get in the way?

[lead_org Microsoft MVP Contributor]

these CPU are not cross compatible. 

[ajkula66 Guru]

As lead_org said, that swap won't work.

The fastest CPU that you can put in an A31/p is P4M 2.6 Ghz, SL6WZ, but these are still pretty expensive..

[lvlenovo]

Voltage, FSB speed and socket are all within spec match to the P4M. Asking why will not change production that has ended over 8 years ago...

 I saw one Northwood pin mod using a jumper, and another taking out a pin. Apparently both only work with 400FSB Northwoods. Again for less than 10$ it may be worth a try.

Anyone make a pin mod work?

[ajkula66 Guru]

"Worth a try" holds true only if you don't blow up the board, which you likely will.

I've been toying with similar stuff when these babies were new and haven't gotten very far.

Good luck.

[lead_org Microsoft MVP Contributor]

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lvlenovo wrote:

Voltage, FSB speed and socket are all within spec match to the P4M. Asking why will not change production that has ended over 8 years ago...

 I saw one Northwood pin mod using a jumper, and another taking out a pin. Apparently both only work with 400FSB Northwoods. Again for less than 10$ it may be worth a try.

Anyone make a pin mod work?

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if you don't mind blowing the CPU and the motherboard, then you could try it. If i am you i would trust Ajkula66, since more thinkpads have gone through his hand than probably most Lenovo consumer in USA. 

if the mod was possible, then people in the Thinkpad community would have done it ages ago. 

[lvlenovo]

I did not find any postings about the mods, so no harm done in asking!

Likewise, I did not find anything, both in German or Chinese sites, about successfully changing the PPL clock rate.

It seems that this age of business machines are not made for fun...

Summary for the a31 ( Please correct if necessary )

- CPU can be upgraded to a P4M 2.6GHz or Celeron M if the heat sink is changed accordingly.

- no overclocking possible by either modifying pins or PLL tweaking

- tpfancontrol can be used

- the system can be underclocked by removing the battery or

- underclocked using CPU Frequency scaling (linux)

- HD video will require fan operation ( my 2.0GHz  is fine with 720p, but chokes with 1080p) 

[lead_org Microsoft MVP Contributor]

not sure about system underclocking when removing the battery part.

Regarding FHD video playback, it is just a limitation of the CPU and the GPU, there is not much you can do about that.