photonboy :
The TDP is not the same as the amount of power consumed. It's a way to group products in a group such as "design the socket to handle power draw up to 130W".
The 980X has 50% more cores thus will consume up to about 50% more power (which means 50% more heat energy to dissipate). Since it's a liquid cooler it's probably fine but you will still have to double check the temperatures.
(check with Prime95 or converting video whilst using all cores in Handbrake. ensure 100% usage. the GAMING performance need not be checked as it should be about the same as now because most games won't use more cores. So no gaming advantage in general, but also no temperature difference that's notable.)
*But what's the POINT?
The main advantage is that it has SIX cores but that's not going to help most games as you need FASTER cores not more of them. You need to upgrade to something like an i7-7700K if you want to notice a difference.
Now the SINGLE THREAD performance of the i7-980X is rated higher than the i7-920 however they are overclockable so both are capable of achieving similar performance once overclocked. (the i7-980X is a higher frequency at stock but the i7-920 has more headroom so likely can match the i7-980X per core).
So don't spend much money on the i7-980X.
I would have to disagree. My xeon e5-2628L v4 only has 1,7GHz with 12core 24thread. It can run new AAA games that was famous for i5 killer (Battlefield1, Mafia 3, Watchdogs 2, Farcry primal) and normal AAA games (The division, Battlefield hardline, Resident evil 7, Fall out 4) with no problem and no need special setting (just set it as 1080 ultra and run).
As you can see, my core is extremely low, if what you said is true, then my cpu should have lots of trouble, but reality said otherwise. It can optimized my GTX 1060 without any bottleneck. Unfortunately I have not tried very old game that not support hyperthreading as I do not see the reason to look back at the game that I will never touch again.
Here are links to my gameplay, I only made Battlefield 1
https://www.youtube.com/watch?v=zIqUPOiEbUk
and Farcry primal
https://www.youtube.com/watch?v=OKL6dHKhoMg
Even first generation xeon 2,2GHz 6 core 12 thread can still aced those i5 killer games. Q4 2016 game maker are starting to optimizing more threads, which caused i5 killer trend, they might forgot to adjust it backward. Don't get me wrong, i5 can still run those games, but you need to do a bit adjustment in the game in order to prevent fps drop. As far as I know, Battlefield1 needed 6 thread to run properly without adjustment.
Then again, back to OP. I do not think it will improve a lot since you already have 4 core 8 thread cpu (except for watchdogs 2). Upgrade it into 25% faster 6 core 12 thread cpu will only improve around 10% in cpu performance. If its cheap enough, then its worth it. Your heatsink should be fine since its water cooling. Yeah it would run hotter, but your heatsink could handle it just fine.