ata only getting 33 instead of 133

[dalibor kollar]

Hello,

I'm using PC-BSD 7.1 based on FreeBSD 7.2-PRERELEASE #12

dvd burner: ASUS DRW-1814BL -
http://www.asus.com/product.aspx?P_ID=0S8SJw9jibmKbMn5
MB: ASUS K8V-X SE - http://www.asus.com/product.aspx?P_ID=lzDXlbBVHkdckHVr

dmesg says:

acd0: DMA limited to UDMA33, device found non-ATA66 cable
acd0: DVDR <ASUS DRW-1814BL/1.14> at ata1-master UDMA33
acd0: FAILURE - INQUIRY ILLEGAL REQUEST asc=0x24 ascq=0x00
cd0 at ata1 bus 0 target 0 lun 0
cd0: <ASUS DRW-1814BL 1.14> Removable CD-ROM SCSI-0 device
cd0: 33.000MB/s transfers

my chipset (VIA K8T800) is not amongst chipsets listed in manpage of ata
controller driver. It says when chipset is not supported, UDMA is set
automatically to UDMA33. I'm using 80 pin cable. 100%.

"atacontrol mode acd0 UDMA6" returns: "current mode = UDMA33"
"atacontrol mode acd0 PIO4" - mouse becomes extremly jumpy and there is no
significant performance gain.

disabling 80pin cable check in loader.conf through
"hw.ata.ata_dma_check_80pin="0" gives me UDMA66 after reboot.

The question: how do I enable full speed of UDMA133? Is it possible at all?
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dalibor