AHCI Timeout errors on Intel Patsburg

[Alexander Motin]

Hi.

 > is 00000000 cs 00000000 ss 00000001 rs 00000001 tfd 40 serr 00880000

This line (ss and rs fields) tells me that device haven't confirmed 
completion of one NCQ command. Bits set in serr field mean "10b to 8b 
Decode Error" and "Link Sequence Error". I would suggest that something 
wrong with the link quality. That may explain why reducing speed helps.

-- 
Alexander Motin