Mac – Can a Mac Pro be upgraded from a 5150 CPU to a 5365

Short answer:

The lowest end Mac Pro that can be upgraded to a 2.93 12-core Westmere is the 2.66GHz 12-core Westmere.

Long answer:

The single socket Nehalem and Westmere Mac Pros literally have one socket. Aside from that, most of the lower end configs ship with a 1066MHz memory bus instead of a 1333MHz bus. In order to upgrade to a part that uses faster ram you will need to replace all your ram, and probably solder some resistors to change the clock multipliers on the board.

Without SMD soldering you will need to match the bus speed of the processor, which means if you have a 1066MHz memory interface the highest end part you will be able to install is are quad core 2.66GHz Xeon E5640s. There is also no guarantee the firmware will actually initialize it correctly, though odds are good that it will.

You should be able to boot without a graphics card, but that will be an easy part to find. The Wikipedia article is quite good about processor families so you have several options there. The apple power supplies are top notch, but you might find an equivalent.

Have you considered buying a scrap Mac Pro for it's power supply? I would be hesitant to spend money if I were not sure of the provenance of the stripped Mac Pro you have. (If the Mac worked, why strip the CPU, GPU and power supply? )

Good luck with your frankentosh!