TA-1000: PCIe* Link Width Can Downgrade to x4 or x2 with Add-In Card
TA-1000: PCIe* link width can intermittently downgrade to x4 or x2 with add-in card (PDF) 
This document describes products that can be affected, the problem description, the cause, and workarounds. This issue is fixed in the current BIOS release.
Size: 111 KB
Date: May 2012
Note: PDF files require Adobe Acrobat Reader*.