Upgrade CPU Pentium M 705 to Pentium M 780

AKLAL

Estimable
Nov 5, 2014
9
0
4,510
0
I have a hp laptop zt3200 with pentium m 705 1.5 ghz cpu 400 mhz ram. Can I upgrade the cpu to pentium M 745 1.8ghz cpu 400 mhz ram or 780 2.27 ghz cpu 533 mhz ram?
 

Cristi72

Estimable
Jun 25, 2014
155
0
4,710
40
Hello,

Your best bet is M745 (or any FSB400 Pentium M-7xx CPU), M780 has 533MHz FSB. On the other hand, you have a HP, so most likely it won't work.
 

AKLAL

Estimable
Nov 5, 2014
9
0
4,510
0


My need to upgrade CPU is due to NX bit not enabled in M705 and I can't install windows 10 TP. I think NT bit is enabled only in M7xx 533MHz FSB processors. Is there any M7xx 400MHz FSB processor that supports NX bit? What are the likely problems if I replace the cpu with a 533MHz cpu alongwith the ram of 533Mhz? Can somebody explain the bios related problems?

 

Cristi72

Estimable
Jun 25, 2014
155
0
4,710
40


Comparing to a CPU with 400MHz FSB, a 533 MHz CPU needs another multiplier table and other CPU voltage range, that's why the motherboard needs at least a BIOS upgrade for adding the new CPU microcodes. While a desktop motherboard can be sometimes "tricked" to accomodate CPUs not officially supported by manually entering the FSB value and multiplier, a laptop motherboard gives no means to manually modify the multiplier or the FSB frequency.

HP (and all laptop manufacturers as well) has no incentive to assure support for newer CPUs in their already released motherboards; it's basically this: you need more speed, buy a new laptop. They have a good point to do this: maximum compatibility.
 

AKLAL

Estimable
Nov 5, 2014
9
0
4,510
0


As used Pentium M 7xx CPUs from china are available for less than $10, I have ordered one M755 which is 2GHz with 400Mhz FSB and one M770 which is 2.1 GHz with 533MHz FSB. As per your advice, M755 should work with less or no problems. M770 specs says it can work down to 800MHz when idle. Therefore, there is a possibility of auto down clocking of M770 to work at 100 MHz FSB. It's my wilde guess as M705 (the existing cpu) , M755 and M770, all three are shown compatible with Intel chipset 855PM (ref cpu world). I'll do this as an experiment. It looks a case of down clocking which is acceptable to me if Windows 10 can be installed. If down clocking succeeds, M770 will be working at 1.58 GHz that is very near to M705 working at 1.5GHz. If M770 fails, I'll use M755 to have about 25% boost in performance . My immediate concerns are about BIOS updates if needed. Also the quality of used CPUs coming from china may add problems.
 

Cristi72

Estimable
Jun 25, 2014
155
0
4,710
40


Unfortunately, your assumption is wrong, as the CPUs are modifying the multipliers when dinamically changing frequency, not the FSB (Front Side Bus), which is a fixed value and is directly linked with the chipset's internal clock (BCLK). Desktop motherboards (not all of them) have the possibility to modify the FSB value independently from the BCLK, laptops can't.

The main issue with 400-vs-533 FSB is not the frequency itself, but the CPU voltage table. In theory, all 533-667-800 MHz FSB CPUs should work in 400 MHz motherboards with a lower resulting speed (the multiplier remains the same), but they have different voltage requirements at the same given speed and, if the motherboard is not giving the proper voltage, the system will not work, that's why a BIOS upgrade is a must. If the manufacturer is not willing to release such updates, you're out of luck.
 

AKLAL

Estimable
Nov 5, 2014
9
0
4,510
0


As per M Processors list on wikipedia processor M705's voltage spec is 0.956–1.484 V and M770's voltage spec is 1.26 -1.357 which well within limits. The chipset 915GM supports both 400 and 533 MHz FSB and processor automatically adjusts. However, 855PM/GM dosn't seems to support two FSBs. I have searched on internet but could not find anyone giving info about putting 533 fsb processor in 855 chipset. Chances are very low if the processor will work without BIOS update which I don't know if available. However, I'll give it a try. Let us see what happens.
 

Alejandro RDZ

Estimable
Aug 11, 2015
1
0
4,510
0
Hello, yes you can upgrade the proessor to that, i have a BenQ Joybook 700, with a Pentium M 735 1.7 FSB400 21 watts, and chenge for a Pentium M740 1.73 FSB533 27 watts, and works perfectly, now i upgrade the processor to a Pentium M770 brought on ebay per 10 bucks. my chipset is an
intel odem i855pm-333, so is that my experience with diferents FBS and voltage(that say wiki,)
my best regards
 

AKLAL

Estimable
Nov 5, 2014
9
0
4,510
0
After a long wait, last week I replaced existing CPU M705 (400 FSB) with M770 (533 FSB). The new CPU is working fine when run on Battery except that fan is now working on full speed trying to cool the new CPU.. When Laptop is run on mains, it shuts down after some time. It seems the power requirement of the M770 can't be met with existing power adapter. I am thinking to connect two adapters in parallel. Any suggestion in this regard is welcome. Due to heating CPU, other components may also be affected. However, one thing has been established that zt3200 MB can take M770.

Next I tried to upgrade Windows 7 that currently runs on this laptop to Windows 10. The upgrade aborted without giving any message and it removed the Genuine status from the existing Windows 7 Pro. That had been a funny behaviour. Now the status has become unknown. However, I am able to use all programs without any message. If you have come across such a case, kindly share it.
 
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