I have an onboard SATA controller from Silicon Image too. And it just works with RedHat 8, there is no newer driver for that [badword] thing!
(It's stupid to run an AMD64 with a 32bit OS...)
Due I have a Barebone, there is no PCI slot left, so I'm runnig this old, but supported Distro.
I will never buy anything from Silicon Image nor NVIDIA !
You can try to replace the mainboard with another controller, replace the SATA HDD with a ATA or live with the seperate controller card.