I think that I have got latest bios on it. I download bios update utility from lenovo web site. But when I start it I have got a massage that the bios not need to be updated. Where I can find moded bios?

Hello,
I have got Thinkpad r50e with celeron m 340 inside. I try to upgrade it to pentium 745 sl7en but r50e wont boot. Fan is working, pover led is on but screen is black. On old cpu is working fine. Have you got any sugestion how to fix it?