How many SATA HDD can Mac OS support"

I have been reading that the onboard SATA controllers on motherboards are quite poor quality and that a separate SATA controller card will give you MUCH faster performance.

So, I did some research and came across this cryptic comment about a card I was looking at:

Port Multiplier Support

Thanks to the built-in support for SATA Port Multipliers with FIS-based switching or Command Based switching, this card allows you to easily connect more HHDs/SSDs at once*.

*Note: The SYBA SI-PEX40071 PCI-E controller card supports 3TB and 4TB GPT drives. Mac OS is limited to four ports active at one time.

Now, I don't actually want any port multipliers, so this may be nothing.

What I want 8 HDD on 8 ports. Ideally, using the SATA ports provided by the chipset on the motherboard. So I guess I also want to know if anyone has any idea how good the SATA from the motherboard chipsets are? Are some motherboards better than others?