no booting after changing cpu (md41700)

[knomic]

hi,

maybe someone of this forum can help me.
i try to update the cpu of an old medion notebook called md41700.
standard a celeron@2,66Ghz is running in this machine and i try to update it to an p4m SL6FH with 1,8Ghz.
after modifing the heatsink and starting the notebook the cpu ist recognized correctly in the bios and the startscreen.
but after the startscreen no booting is possible. i only get a blackscreen.
is there anything i can do by changing the bios?

thx for help

knomic