The Seagate 1TB hard drive on my late 2009 IMac failed recently after 4 years. I replaced it with a SSD. The pick up in performance has been phenomenal but much to my surprise some issues that plagued me for years got resolved. Sleep mode now works the way it should by staying in sleep and my logitech mouse works smoothly (magic mouse doesn't fit my hand as well). It was jerky before and would disconnect in sleep.