first I want to point out the cpu is not soldered in the socket.
I have a stepnote nm3900w laptop with a FIC NM3500W motherboard and a Mobile Intel Celeron M 350, 1300 MHz (13 x 100) Package Type 479 Ball uFCBGA / 478 Pin uFCPGA
I would like to upgrade it to the fastest possilbe processor it can handle. Maybe this one>Intel Pentium 4 Processor 2.53 GHz (Socket 478) SL6S2.
Is this possible?
Would I have heat and/or bios problems ?
And of course will the upgrade fit ok in the socket?
I don't recommend it. You'd be literally rolling the dice. Laptops are extremely difficult to upgrade the cpu. Even the heatsink may not work with a faster, warmer cpu. I would leave it alone unless you can add some more ram. But if you want to try it, checkout the SL789 mobile cpu at Starmicro for only $10 plus shipping. Or an even safer gamble might be the IMC390 celeron for $21. Just be aware that Starmicro won't accept any returns due to compatability issues, but it's a small gamble for the dollars spent.