GA-x58a-ud7 slow CD on intel ich10 port

[snofte]

Booting from CD (all bootable cd-s, tried many), take ages ( approx. 1 min to boot)
Using sata port 0, thats the intel port. Switching to gigabyte sata port 8, and all is fine.
Also fine using sata port 8 (marvel).  Whats wrong witn the intel ports ?
Bios setting for port 0-3 set at "native" and ahci.     

[snofte]

SOLVED !
This problem started after I installed a iocrest pcie card with 4 sata 6b ports (marvell 9235).
Taking out the card, cd boots fast. Card in place, cd boots very slow when connected to intel-ports.
First workaround:  Connecting cd to marvell 9128 port, it boots fast !
Did not like this as final solution, so searched for other solution.
Found final workaround:
Setting bios setting for "XHD" (extreme hdd) to enable. This seems to be for Raid, but I dont use raid at all.  A fresh boot, and windows found new hardware, asked for drivers, I pointed to intel ahci-drivers, and it installed ok. After this the cd boots fast on intel-port and also on gigabyte ports. !!!!
Problem solved !!
Can anyone explain ??

[shadowsports]

Typical causes... without researching your board. 

PCIe bandwidth is shared  between selected SATA port and slot.

If a second slot was used...  that the slot only operates at half speed when the primary slot is populated.

If you're using a lower end card, bus bandwidth could be lower that expected.

The driver can improve performance in the OS, but not at the BIOS level.  It doesn't exist there.