Buy Skylake CPU or overclock owned CPU?

Moving to an Intel i5 or i7 would yield the greatest performance gains, but would cost a lot more than overclocking what you currently have. If you can only afford up to an i3, you might not want to bother as that is more of a sidegrade, at least for video editing, with games that don't scale well across large numbers of cores seeing a bit of a performance boost.

Overclocking isn't difficult but how far you're going to get is going to vary depending on what sort of cooler you get and your motherboard. Your board isn't the absolute worst, but it won't have the power phases to do very heavy overclocking, so you're not likely to get up to 5GHz or anything like that. If you're worried about CPU heavy game performance, you may also find that overclocking simply won't be enough to make any big improvements. A lot of CPU heavy games that perform poorly on the FX do so due to AMD's poor per core performance. Clock for clock, AMD cores are only about half as fast as an Intel core at the same clockspeed, and you're not going to be able to overclock high enough to close that performance gap if you're playing games that rely heavily on one or two cores.

This really depends on how fast you want stuff to render or if you really just want to get into overclocking. Honestly, if you are interested in it and find that the overclock would be a better investment, then stay with that. If you want an overall better system and don't really want to or have an interest in overclocking, then just upgrade to the proper hardware you need for the job(s) you do. IMHO, I don't care for AMD anymore after going with Intel. The processors are mush faster in single processing and stomp most, if not all, AMD CPUs/APUs in this category. If you go with a decent i7, then not a single AMD CPU can keep up in single threaded processes. This is super nice and needed for games, but multi-threaded processes are more needed for rendering. Only i7s and Xeons, on the Intel side will have this and they will prove to be much better than AMD. But, depending on how much you game vs. how much you render, you might just consider going with a Xeon or an i7. Beware though, you can't OC Xeons and they can have a pretty high price tag depending on what model and version you get. Both have hyper-threading and will be great for rendering, but unlike Xeons, you can OC i7s as long as they have the 'K' designation in their model number. Keep in mind, that if you go with the Skylake processors, then you are really only investing in the chipset and socket since the processors are the same as some of the Haswells and Devil's Canyon chips in all performance and power consumption. iGPU is really the only thing, outside of socket format, that distinguishes the Skylake series from the others I mentioned. If you will have no dedicated GPU (Graphics card) in your system, then the better iGPU in the Skylake processors will be better for you. Otherwise, it will not be used if you have a dedicated GPU in your system.

If all of that is too much or too expensive, then upgrade to a 990 chipset with AM3+ socket and get the FX-8350. It games pretty well and will have more than enough power to render well being an 8 core/8 thread CPU. This was not to bash AMD since their FX CPUs are actually pretty decent, but they're old and on dead sockets and will not keep up with Intel CPUs (if you go with a moderate to high i7 or Xeon with hyperthreading).

The 'K' versions are the only ones that allow you to overclock via the core multiplier, so if you wanted to keep your i5 for a long time and then just overclock it when you think it is a little slow, that's fine. However, I recommended the i7s because they will last longer and perform much better for your rendering than an i5 will. In regards to gaming, they will perform about the same. So, from a production aspect, the i7 will be faster for longer due to hyper-threading that the i5 will not have. Also, the 1151 socket is the newest that Intel is making for, so you won't have to worry about that going away anytime soon.