Difference b/t OC Black & HOF

[nomonater]

So I've been browsing for a new graphics card to replace my slowly aging EVGA 770 and have been looking into the 980 TI series of cards for a while now and I was wondering the difference between GALAX's two 980 TI series one being the 980 TI OC Black Edition http://galaxstore.net/GALAX-NVIDIA-GEFORCE-GTX-980-TI-OC-BLACK-EDITON-6GB_p_86.html and the 980 TI HOF Edition http://galaxstore.net/GALAX-NVIDIA-GeForce-GTX-980-Ti-HOF-6GB_p_82.html.  I mean this of course what is the difference other than the obvious which is the difference in fans and heat pipes.  Basically what makes one 50 bucks cheaper.  Also if I were to buy one from GALAX could I at a later date buy a waterblock for their card from them or would I have to turn to a third party for that.  Also on another note how long should I expect a TI model to come out for the new Pascal series of cards?