[SOLVED] Laptop not starting after CPU upgrade

Aug 13, 2021
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Hello there.
I have upgraded my old laptop today from Intel Core i5 2450m to Intel Core i7 3630qm, to give it a new life.
Please note that the laptop model I am talking about is a Toshiba Satellite L855 S5240, a laptop that has the compatible socket and chipset(Mobile HM76 Express Chipset) for the processor I want to install.
Sadly, when I press the startup button, it just starts and shuts down, while on i5, it still works. I have the latest BIOS version and I performed a BIOS reset as well(by ejecting the CMOS battery and putting it back after a while), but I wonder why it still doesn’t work, despite all these attempts?
 
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Solution
I upgrade laptop to i7 with that exactly same motherboard long time ago. Do you already have latest bios with microcode update?

https://support.dynabook.com/support/modelHome?freeText=3385532&osId=3333616

Double check that it is the right product number, make sure you have battery atleast 50% and power cable connected and download latest 6.70v if you dont already have.
If your already on latest bios might be issue with the cpu itself. I dont remember adding cpu microcodes manually to the bios file and just upgrading to latest was succesful.

EDIT: overheating might be issue later on make sure to use good quality thermal paste and even laptop cooling pad if needed
While the socket may fit and chipset may support it, Laptops are MUCH different than desktops in terms of upgrades. If the laptop was not ever offered with that processor then it's very likely there is no BIOS support for it. That i7 has a higher tdp as well, the laptop's motherboard may not be able to provide the power it needs, as well. If thats the case (which it probably is) you're out of luck.
 
I upgrade laptop to i7 with that exactly same motherboard long time ago. Do you already have latest bios with microcode update?

https://support.dynabook.com/support/modelHome?freeText=3385532&osId=3333616

Double check that it is the right product number, make sure you have battery atleast 50% and power cable connected and download latest 6.70v if you dont already have.
If your already on latest bios might be issue with the cpu itself. I dont remember adding cpu microcodes manually to the bios file and just upgrading to latest was succesful.

EDIT: overheating might be issue later on make sure to use good quality thermal paste and even laptop cooling pad if needed
 
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Solution
That is actually weird, the microcode matches :https://support.microsoft.com/en-us...-updates-547a9fa2-7f24-3172-795b-51a956faed22

There is alot of samples running i7-3630qm on L855 which all have that exact bios version: https://www.userbenchmark.com/System/Toshiba-Satellite-L855/210

Are you running 1066mhz or 1333mhz ram? that i5 supports 1066mhz ram but i7 needs minium 1333mhz (which is no problem with desktop systems but laptops can have all kind of shenanigans). Do you have 65 or 45w ac adapter?
 
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All RAM is at a frequency of 1600mhz. Also, the adapter has proper wattage as well. I might try again today with the upgrade, but only with one RAM stick and see if it works.
 
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All RAM is at a frequency of 1600mhz. Also, the adapter has proper wattage as well. I might try again today with the upgrade, but only with one RAM stick and see if it works.


Pretty sure that wont help. You could try refunding the chip maybe its damaged. There is still chance its something else too. My L855 motherboard might of been slightly different, but i went from i5 To i7 without problems.

You can take pic of the motherboard and try find part number, also what south bridge chip it has?
 
This model indeed has HM76 chipset. It is compatible with third gen, but sadly, the CPU basically doesn’t work most likely since the laptop shut down one second after start up.
I have tested without RAM sticks at all and it started, but ofc without anything to see on the screen. So basically the CPU is basically broken when it comes to memory addresses most likely.
 
This model indeed has HM76 chipset. It is compatible with third gen, but sadly, the CPU basically doesn’t work most likely since the laptop shut down one second after start up.
I have tested without RAM sticks at all and it started, but ofc without anything to see on the screen. So basically the CPU is basically broken when it comes to memory addresses most likely.

Does cpu-z show HM76?