recently upgraded my PC, got a new mobo (ASUS x99-Pro) and proc (i7-5930k) and noticed that when I jump I slow down mid jump, and when I levitate, I don't go up and down like normal, just kinda vibrate really fast.
I have noticed weird issues with different PC. I have the same experience as you, but in addition when I fall I will never take damage. I just float gracefully to the ground no matter the height.
Try throttling your frame rate. EQ was meant to be played on single core pieces of shit computers (by today's standards.) Fast bouncing and odd movement issues are normally a sign of too much FPS or bad network connection.
