PCI Express eSATA Controller help

[volxstu]

My computer knowledge is a little lax to say the least. I want to convert an old Power Mac (2008) PCI Express to house an eSATA Controller.
Question is are all PCI Express ports universal? Most say that they are Mac compatible but dont list them on the OS compatibility list. I presume that is because they dont provide firmware for RAID use?
Also why do they fluctuate in price so much? Do they differ in reliability a lot?

 

[Focus Owner]

I have one in my pc and it don't work no drivers available for it. thats on windows, its due to a lack of all markings so unable to choose drivers on cd