Minergav98

So today I tried over locking my 60hz TV that I use as a monitor. Somehow I was able to get it up to 127hz without any problems. At 128 the display becomes distorted. I was planning to just keep it at 80hz, but my question is what should I crank it to and how will this affect the lifespan of my TV? I am planning to hopefully get a 144hz gaming monitor this year.