Cant change (U)DMA Mode of my HDD

[Sebastian Buschjäger]

Hi,
I'm using FC9 on a 64bit machine. Up to now, everything runs fine except of my CD/DvD drive. Burning or ripping a CD/DVD lets my CPU jump to 100% and it takes about 20min. 
"/sbin/hdparm" says DMA is enabled, so I believe my CD/DVD drive is working as it should. I believe the problem is with my HDD's. Both work in UDMA Mode 2 (same as my CD/DVD drive), whereas my HDDs are capable of Mode 6.
DMA is working, because hdparm gives me benchmarks around :
Timing cached reads:   888 MB in  2.00 seconds = 443.32 MB/sec 
Timing buffered disk reads:   88 MB in  3.03 seconds =  29.00 MB/sec
for both HDDs.

So, the strange thing is, that I cant change the(U)DMA-Mode of my HDDs. Here is some hdparm output, maybe you know what to do(output is nearly the same for sda and sdb):
/sbin/hdparm -i /dev/sdb

/dev/sdb:

 Model=Maxtor 6L160P0                          , FwRev=BAJ41G20, SerialNo=L30Y435G            
 Config={ Fixed }
 RawCHS=16383/16/63, TrkSize=0, SectSize=0, ECCbytes=57
 BuffType=DualPortCache, BuffSize=8192kB, MaxMultSect=16, MultSect=?16?
 CurCHS=16383/16/63, CurSects=16514064, LBA=yes, LBAsects=320173056
 IORDY=on/off, tPIO={min:120,w/IORDY:120}, tDMA={min:120,rec:120}
 PIO modes:  pio0 pio1 pio2 pio3 pio4 
 DMA modes:  mdma0 mdma1 mdma2 
 UDMA modes: udma0 udma1 *udma2 udma3 udma4 udma5 udma6 
 AdvancedPM=yes: disabled (255) WriteCache=enabled
 Drive conforms to: ATA/ATAPI-7 T13 1532D revision 0:  ATA/ATAPI-1,2,3,4,5,6,7

 * signifies the current active mode

[root at Pille-Desktop Pille]# /sbin/hdparm -X70 /dev/sdb

/dev/sdb:
 setting xfermode to 70 (UltraDMA mode6)
SG_IO: bad/missing ATA_16 sense data::  70 00 05 00 00 00 00 0a 00 00 00 00 24 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 HDIO_DRIVE_CMD(setxfermode) failed: Input/output error
[root at Pille-Desktop Pille]# /sbin/hdparm -d 1 /dev/sdb

/dev/sdb:
 setting using_dma to 1 (on)
 HDIO_SET_DMA failed: Inappropriate ioctl for device
 HDIO_GET_DMA failed: Inappropriate ioctl for device

Just to make it clear, I'm using all HDDs and the drive with IDE. HDD primary/drive as slave. I just tested the Ubuntu Live CD, and there it worked. Also I searched around google, found out that some users noticed this problem in F7 and F8 but not in F6, so I think there should be a way to get it working like it did in F6, shouldnt there?
Maybe, and just maybe there are some wrong parameters in my BIOS? I mean, okay Ubuntu and WinXP are working, but with PC you never know ;)

Some Hardware Informations:
AsRock  939Dual-SATA2
AMD 3700+ (single Core)
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