How to change acer aspire 5551 cpu processor

Not possible.

you can not upgrade laptops.

you upgrade by purchasing a new laptop

the tri core cpu you have is the highest performing cpu available for that Acer 5551, see from the Acer website:

AMD Phenom™ II triple-core mobile processor N830 (1.5 MB L2 cache, 2.10 GHz, 1333 MHz FSB, 35 W)
AMD Turion™ II dual-core mobile processor P520/N530 (2 MB L2 cache, 2.30/2.50 GHz, 1066 MHz FSB, 25/35 W)
AMD Athlon™ II dual-core processor P320/N330 (1 MB L2 cache, 2.10/2.30 GHz, 1066 MHz FSB, 25/35 W)
AMD M880G Chipset


Dry

For those that say its not possible are talking rubbish. I upgraded my Acer 5551 to the N830 without any issues apart from buying a higher powered charger (95W) as that's the one that Acer supply with the Laptop when it has a N830 fitted.

Hi  

CLOSING due to age... but please start another thread if you are still having problems , which I will answer promptly...

All the best Brett