I could not find the specs for the sabertooth 980 but the 990 has 2 different sata chipsets. One SATA 6Gb chipset and one SATA 3Gb chipset. You may want to check your board as well and make sure you are connected to SATA 6Gb ports.
Also not all sata chipsets are made equal. Intel chipsets will give the best performance some other sata 6Gb chipsets will barly get SATA 3Gb speed. I have a Z77 MB adn it has intel and as media SATA 6Gb chipsets. The intel ports are fast but the as media ports only get about SATA 3Gb speeds.
