Which SATA port to use for Intel SSD with Dell Optiplex 990?

I just bought an Intel 520 Series SSD and I have 4 SATA ports on my Dell Optiplex 990. SATA0 - dark blue, SATA1 - black and SATA2 and SATA3 - white. On the datasheet of Dell Optiplex 990 I can not see which of those 4 ports are SATA 2 and which are SATA 3 for my SSD.

Anyone could help me? Thank you.