Pentium M

Hello there!
I have to disassemble an old Vaio laptop (dead HDD), and I was thinking of changing the CPU as well. It's a Pentium M 730 (1.6GHz, FSB 533). I would change it with a Pentium M 755 (2GHz, 400FSB). The 755 has lower TDP (21 vs. 27), but an earlier stepping (B1 vs. C0).

Do you guys think the 755 would be a bit cooler or the stepping would make it hotter??
Thanks!

 

25% reduction in TDP I'd say it runs cooler.

 

Hi HTWingNut!
I'm not sure because the 755 is an earlier model than mine. How is it possible that it is both faster and cooler?

 

730: 533FSB and 755: 400FSB, that might explain the TDP difference. Have you considered the Pentium M 760, same clock speed as the 755 but with a 533MFSB.

 

Yes I have. But my first need is a lower TDP, performance comes second.
I think I'm going with the 755, hoping everything'll go smooth!
I'll post back the experience!

 

Suggestions:
1- get the 760, and undervolt it using RMClock. Pentium CPUs undervolt very well and that will lower the temps and DTP considerably.
There is an extensive guide on how to use RMclock in the forum.

2- Instead of the Pentium M 760, go for the M 725 or the M 735 and pin mod it so it will run with an FSB of 533MHz instead on the factory 400MHz. You then use RMclock to lower the voltage and temps.
There is a detailed guide on the forum showing how to do the pin mod too. Use the search option to find it

 

Mmm, that's another possibility... I plan to use RMClock, that's for sure! I always use it and it's awesome!

One more question is: will the Bios take a 400mhz fsb cpu? The cpuid is different between the two Pentium M families (400 vs 533). How to know?

 

Why 760? Why not 770 or 780? They have very similar prices as used cpus and they have the same TDP. So the OP should go all they way to the fastest CPU of that series.

ps: I used 770 (2.13 GHz) for around 2 years and it worked very well with Win XP Pro.


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Now the point is: the 7x5 family has a different (older) stepping and cpuID than the 7x0. It appears that the 7x5 cpuID was the same used for 7x0 engeneering samples, the OEM version of the 7x0 family being produced with the later C0 stepping and cpuID.
Do you think my Vaio will take the older 7x5 cpus or must I stick to 7x0 family?

 

It will take the Pentium M CPU with 400MHz FSB and it will run as intended. If you wished it, you could pin-mod the 2GHz CPU to 2.66GHz, but I doubt that it would be stable.

 

It is easier to find a 760 than the 770 or 780. Also I think the 770 and 780 would be much more expensive as they have been produced in a small number.

It should work. If it doesn't you can always resell the CPU

The only way to reach 2.66GHz is to up the voltage by a bit. Doing so will increase the DTP considerably. The safest options are the 725 and 735. There are a lot of people who did the mod and succeeded with the 735.
I did the mod with the M 715 (from 1.5Ghz to 2Ghz) and a celeron M 350 (also from 1.5Ghz to 2Ghz). I was even able to undervolt the 715 after mod by a lot.

 

Noric-

Are you getting the replacement CPU for free, or do you have to buy it? Because there are really two issues here:

(1) Is the 755 faster / cooler than the 730? Yes to both.

(2) Is it worth the money to upgrade? No, absolutely not. Not even if you could get a 755 for 10 bucks. There is no point in spending money to upgrade a hardware platform that is already obsolete. Unless you get the 755 CPU upgrade for free, then I say just continue to use whatever you have now, until you run it into the ground and it dies.

 

Well, the thing is different to me. A pentium M is WAY WAY WAY better than an Atom (even dual core), especially when it comes to single threaded application (almost every application of the everyday use, Internet, Office, etc.) where Hyperthreading doesn't help. On a 13" notebook I don't need any performance more, just I'd like it to run a bit cooler.
If I can get a tiny performance boost, 5-10 degrees less (maybe with the help of a good thermal paste), and say 30 minutes more on battery, for me it's worth spending 50 bucks or so. Don't you think so?

 

agreed, if the laptop is in good condition, especially since its an ultraportable, it would be a great netbook alternative. but then again, is the battery in good condition? sometimes a new battery can make it pointless cost wise.

i just "refurbished" an old vaio i had sitting around, 1.7 pentium M (dothan) i bought 1gb of ram for 99pence and i took a new old stock hard drive i had sitting around and gave it to my girlfriend's mum- she just wanted a laptop for email, skype, and microsoft word so it fits her needs perfectly, even though the battery is dead, because she just uses it like a desktop

 

Wow... $50 for the CPU upgrade? I can't tell you what to do... but I can say that it isn't a smart buy.

(1) You are spending a decent amount of money on a dead platform. I thought that the upgrade would be $10-$15 (and even then, it wouldn't be worth it. $50 is a different story.

You are using an old machine. Something else will break. Something else will need replacing. Any money that you spend on your current machine is money that you won't see again... because you won't be able to carry over any parts, you won't be able to resell those parts.


(2) You're not going to get any performance benefit. The fact of the matter is that small incremental CPU ugprades do not give you any noticeable real-world performance. Your computer won't boot faster. Your applications won't load faster. Your games will not run faster.

Realistically, you need to either leap a generation of CPUs to get performance improvement.


(3) You're not going to get much battery life improvement, either. Your CPU drains only 25% of the total battery draw on your system (the LCD screen is the big culprit, at 50%-60%). So even if your new CPU gives you 10% more efficiency, you're looking at 25% --> 22.5%. That improvement overall, is so small, that it might as well be within the margin of error.



The smartest thing to do with your money is to just save for a new laptop. If you want to improve your cooling and battery life, then the best thing for you to do will be:

(a) Run RMClock, and undervolt your CPU. Note, this is not underclocking... you're not changing your clock speeds, just reducing the amount of voltage going to your CPU to the bare minimum.

(b) Disassemble your laptop, and use compressed air to clean out all of the parts and cooling assembly.

Those two recommendations are something that *WILL* give you immediate noticeable benefits, and are absolutely free. Save your $50 on something that will give you substantial return, like a new laptop in the future.

 

I upgraded my Compaq M2000's cpu from Celeron M to Pentium M 725 (1.6ghz) for like $25, one of my best buys ever. Still working till this day.

Pentium M's undervolt really well. Once undervolted they can run so cool that you can get rid of the system fan. All passive cooling...

Added a lot more battery life too. CPU only uses under a volt at full throttle and idles at .700v

 

I'm back!
Upgraded with a Pentium M 725, pin-modded to 2,13GHz, works like a charm! 15€ very well spent! Also upgraded to 1GHz of ram.

The downside is that in order to swap the cpu of this ing Vaio, you need to unscrew about 50 screws, put in unbelievable places, and disassemble the hole notebook. Otherwise you're unable to take off the heatsink. A very hard job in the end, but funny after all!

Edit: forgot to say that in cinebench-single threaded I now get 1850 points. Not bad at all!

 

Money well spent indeed