Alan Cox wrote:
>> Aug  9 07:41:29 monet kernel: ata1.00: limiting speed to UDMA/66:PIO4
>> Aug  9 07:41:29 monet kernel: ata1.00: exception Emask 0x0 SAct 0x0 SErr
>> 0x0 action 0x2
>> Aug  9 07:41:29 monet kernel: ata1.00: (BMDMA stat 0x64)
>> Aug  9 07:41:29 monet kernel: ata1.00: cmd
>> c8/00:08:fb:7c:a1/00:00:00:00:00/e0 tag 0 cdb 0x12 data 4096 in
>> Aug  9 07:41:29 monet kernel:          res
>> 51/84:00:00:00:00/00:00:00:00:00/e0 Emask 0x10 (ATA bus error)
>> Aug  9 07:41:29 monet kernel: ata1: soft resetting port
>> Aug  9 07:41:29 monet kernel: ata1.00: configured for UDMA/66
>> Aug  9 07:41:29 monet kernel: ata1.01: configured for UDMA/33
>> Aug  9 07:41:29 monet kernel: ata1: EH complete
> 
> Drops to UDMA33 for 40 wire cable.

It drops from UDMA/100 to UDMA/66 for the disk, but stays at UDMA/33 for 
the optical drive.  If I have only the disk on that controller, the disk 
still drops to UDMA/66.

> Looks to me like your cabling is out of spec or you have electrical noise
> problems.

I've tried different cabling solutions, including round and flat IDE 
cables.  What might cause "electrical noise"?  Are 44-40 pin adapters 
reliable?