It isn't just the wattage that's marginal. The PSU quality will be marginal too.
I wouldn't OC a CPU unless I had a custom cooler on it. If you don't do these things properly, you'll end up with problems. Even with OC, the CPU will only be a smidgeon better than at stock speeds. And you'll get overheating problems on top of it.
Just try it and keep an eye on how it runs.