NCQ for nforce4-ultra?

[dieterbsd at engineer.com]

FreeBSD 8.0 amd64
FFS w/softdeps

  Performance writing a single file:

    device    r/s    w/s     kr/s     kw/s wait svc_t  %b
      ada5    2.5  728.0     40.0  93184.1    7   5.5  76

  Copy 4 files from 4 disks to one disk, to test
  write performance when seeking:

    device    r/s    w/s     kr/s     kw/s wait svc_t  %b
      ada5    2.0  556.4     32.0  71213.9   44 114.1 100

NCQ is helping even more than I expected.  Without NCQ, write speed
runs only 6-7 MB/s writing a single file (minimal seeking).  I don't
want to think about how slow it would be trying to write multiple files
at once.  Plus, writing to a non-NCQ disk affects unrelated processes
accessing other disks.  My theory is that the buffer cache gets clogged
up.  This destroys the performance of the entire system.  Processes
hang for tens of minutes.

Unfortunately, neither achi(4) nor siis(4) support the nforce4-ultra
chipset.  Is there a driver I can load to get NCQ with the 
nforce4-ultra?