Dell Precision 690 CPU Upgrade Help

(moved to the desktop support forum)

Hello everyone, I was wondering what would be the best option for upgrading the CPU in my Dell Precision 690. The motherboard model in mine is the 0DT029 (earliest) and I want to know what is the best (or max) CPU I can upgrade this to. I was thinking of a Xeon x5460 but I'm unsure if that will be compatible due to my motherboard model.

Specs of this 690:
Intel Xeon DP 5060 at 3.20GHz with 4MB L2 Cache

6 GB of Fully Buffered DDR2 (FB-DDR2)

EVGA GeForce 9500 GT

0DT029 Motherboard model with the 5000X Chipset

160 GB Western Digital Serial ATA Hard Drive

BIOS Version A08