I installed a new cpu ;Intel Celeron Dual-Core E3300, Freq: 2.55GHz, FSB 800MHz, Cache 1M, Socket LGA 775. When I turned the computer on, everything sounded like it was starting up, but the monitor stayed blank. When I put the old processor back in everything worked fine. My motherboard is an ECS 945G-M3. What are the possible problems? Is there something I need to update first?
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Mate, your board isn't compatible with the Celeron Dual-Core. You'll need a new motherboard for that. I'm sorry, I really am.
Since you already have the CPU, you could try a BIOS flash. It can't hurt, and it may have a "comparable" CPU profile it may recognize that as. You may need to tweak voltages to make sure it isn't getting more than it needs. At this point, what do you have to lose? If it doesn't work, no (extra) money spent, if it does, bonus!