This is a note for people who want to purchase the Dell Precision 490.
The motherboard is adapted with Intel 5000X Chipset. However, the earlier version of the motherboard only supports Intel Dual Core(51xx), means the the Quad-Core (53xx/54xx) is not in support list. This problem is due to the circuit layout. You may need to replace the motherboard from Dell.
Note: The firmware upgrade doesn’t solve this problem. (Test Firmware is A07)