I currently have a Ninja Scythe Mini w/o a fan attached to my cpu which is an overclocked E6750. It is overclocked @ 3.3 ghz and my computer is perfectly stable and has been since i bought my heatsink never crashing. However, I just recently looked at my temps when running near 100% load and the temps averaged 65 C. I didnt use the fan because i wanted my computer to be silent however, seeing the temps like this, should I reconsider attaching the fan back on? even getting another one?
Thanks.

It should be ok since it is still below the thermal limit of the CPU.

I would experiment a little though, drop the CPU down to 3.2GHz and check the temp under 100% to see what the temp drops to I'm guessing 63C. Try it out, I don't think you should notice much drop in performance. If the performance seems fine then keep it there. If not then bump it back up.

Scythe fans shipped with their heatsinks are usually quiet. I would have gone with a full size Scythe Ninja, unless it is too big to fit in your case.

2 option. try to lower vcore if you havent already did. or

orless you got a very cool case put a fan of your cooler and hook it up to a fan controller so you can turn it down to your desire speed. a "little" airflow in the heatsink is much better then nothing at all.

but in general 70C is safe if you prime it to max.