I've got a dual CPU Intel Dual-Core Xeon E5140 system. What's my best option to max the system performance-wise by CPU upgrading. It's an IBM server with LGA771 sockets. It's meant for typical LAMP usage.
The X5492 was the most capable socket 771 chip with quad cores at 3.4Ghz but it is a 150W TDP chip so not everything can take it, you'd also want to ensure it was supported by your BIOS too. Other than that the X5472 was the best 120W 771 chip and the E5472 was the best 80W 771 chip. Hope this helps.