I'm not terribly clued up on this tbh but in terms of fans you'll want some headroom to speed them up as it's obviously going to run hotter as you increase the voltage, which has to be increased to keep things stable at an increased clock speed. Whether they are up to the task or not is probably impossible for me to say as it depends on your system, how well ventilated everything is or even nearby heat sources.
Best place to start is by looking at the temperatures you're getting under load without overclocking, I was told it's wise to back off once you're exceeding 80 degrees although that may vary from card to card. Run a benchmark test, if you've got room to maneouvre and your fans aren't anywhere close too full capacity then gradually start to increase your clock speeds in small increments and see what happens keeping an eye on temperatures at all times.
If it crashes then it probably isn't stable and you'll want to either increase the voltage or decrease the clock speeds upon restarting.
I would recommend not applying the overclock on startup, if you're playing a game that runs fine already or doing something else then there isn't much point and I think you could cause yourself more problems it's unstable. Uncheck that option and the settings should come into effect as soon as you hit apply.
I hope that is somewhat helpful, tbh I would recommend looking into some guides from people who definitely know what they're talking about before starting anything. I take no responsibility for you frying your system as a result of following my advice