Sata/IDE drive recognition problem

[Vizion]

I originally posted to freebsd-questions but, judging by the lack of replies I think I made the mistake of posting to the wrong list - on reflection this seems to be more a question for hardware. Thanks in advance for any guidance.
> 
> While preparing to move a system from i386 to amd 
> architecture The existing system is dual booting i386 for 5.4 
> stable and 6.0. My plan is to remove both systems, preserve 
> my data and reinstall 6.1 amd from cd.
> 
> The motherboard is a FA-K8N51GMF-9 with 3 hard drives 
> installed. 2xSata and 1xIDE.
> 
> Freebsd 5.4 
> #df sees 
> /dev/ad4s1a 
> devfs, 
> /dev/ad4s1e
> /dev/ad4s1f
> /dev/ad6s1d
> /dev/ad6s1e
> linprocfs
> 
> Freebsd 6.0
> #df sees
> /dev/ad0s1a
> devfs
> /dev/ad0s1e
> /dev/ad01f
> /dev/ad0s1d
> /dev/ad4s1a
> /dev/ad4s1f
> /dev/ad6s1d
> devfs
> 
> The CD installer select drives interface for 6.1 RELEASE 
> amd64 recognizes
> ad0 and
> ad4 
> but not ad6.
> 
> For installing 6.1 amd I will need the installer to see all 
> physical devices and existing partitions. 
> 
> The Bios CMOS features show 
> IDE Channel 0 Master WDC WD2000JB
> IDE Channel 0 Slave Lite-on CD-RW
> IDE Channel 2 Master ST3160827AS
> IDE Channel 3 Master WDC WD2000JD
> The Advanced Bios features show
> First boot device CDROM
> Second Boot Device Hard Disk
> Third boot Device Hard Disk
> 
> The Hard disk boot priority sequence options show:
> Ch0
> Ch2
> Ch3 
> root
> shutdown -r
> 
> /var/log/messages shows
> ad0 WDC WD2000JB at ata0-master UDMA33
> acd0 Lite-on at ata0-slave USMA33
> ad4 ST3160827AS at ata2-master UDMA33
> ad6 WDC WD2000JD at ata3-master UDMA33
> 
> How do I get the installer select drives interface to recognize ad6?
> 
> Thanks in advance
> 
> david
> 
PS
I have now successfully built amd64 on /dev/ad0 but not yet mounted ad4 or ad6. While ad4 is "seen" according to /var/log/messages the new build does not "see" ad6 .. does anyone have any ideas how to fix this?
Thanks
David