I am currently using 1 pair of corsair vengeance 2x4GB and 1 pair of g-skill 2x4GB. Both 1600MHz. But my computer seems to only be able to read 8GB of ram. But sometimes it can read 16GB. And i get very high ram usage when it read 8GB. Like around 68% and my game fps will stutter. I upgraded my ram with the 1 pair of g-skill ram, asus gtx 970 and intel core i7-4790k. Can anyone help me with this problem?