CPU Upgrade OptiPlex 755 SFF

Hi Logansrun22,

I don't see that processor listed as compatible. From this thread, here are the compatible processor upgrades for the 755:

Intel Core 2 Quad Q6700 Processor (2.66GHz, 8MB L2 cache, 1066MHz FSB, VT)
Intel Core 2 Quad Q6600 Processor (2.4GHz, 8MB L2 cache, 1066MHz FSB, VT)

Intel Core 2 Duo E6850 Processor (3.0GHz, 4MB L2 cache, 1333MHz FSB, vPro, VT)
Intel Core 2 Duo E6750 Processor (2.66GHz, 4MB L2 cache, 1333MHz FSB, vPro, VT)
Intel Core 2 Duo E6550 Processor (2.33GHz, 4MB L2 cache, 1333MHz FSB, vPro, VT)

Intel Core 2 Duo E4600 Processor (2.4GHz, 2MB L2 cache, 800MHz FSB)
Intel Core 2 Duo E4500 Processor (2.2GHz, 2MB L2 cache, 800MHz FSB)
Intel Core 2 Duo E4400 Processor (2.0GHz, 2MB L2 cache, 800MHz FSB)

Intel Core 2 Duo E2180 Processor (2.0GHz, 1MB L2 cache, 800MHz FSB)
Intel Core 2 Duo E2160 Processor (1.8GHz, 1MB L2 cache, 800MHz FSB)
Intel Core 2 Duo E2140 Processor (1.6GHz, 1MB L2 cache, 800MHz FSB)

Intel Celeron 440 Processor (2.0GHz, 512K L2 cache, 800MHz FSB)
Intel Celeron 430 Processor (2.0GHz, 512K L2 cache, 800MHz FSB)

I purchased a new processor for my OptiPlex 755. The specs are as listed below: Brand - Intel Processor Model - Pentium D 945 Clock Speed - 3.4 GHz CPU Socket Type - LGA 775/Socket T Multi-Core Technology - Dual-Core TDP - 95 W Cache Memory Installed Size - 4 MB Type - Advanced Transfer Cache Bus Speed - FSB Speed - 800 MHz Before attempting to install the new CPU, I upgraded to the newest version of the BIOS, which is A22. When I plug the computer back in after installing, the power button glows orange and the heatsink fan comes on and keeps speeding up until I unplug it again. I cannot boot at all with the new CPU in, but when I put the old one back in, it boots fine. Did I get a CPU that's not compatible or is there something else I need to do to make it work?