I think some people have a misunderstanding of what unparking a core really does.
No on seems to give a good answer so I'll give some hints here and helpful facts.
Fact 1 Yes Windows any version sucks at using a cpu's full potential of cores.
Fact 2 Windows itself fully runs on Core 1. Along with many if it's apps and other programs be it Adobe Reader I.E.
Fact 3 Most games you play don't use all if any extra cores a CPU has nor can they all take advantage of true SLI modes in older games.
Fact 4 If you do unpark you cores yes it will run all cores at their highest potential using power "not feasible on laptops"
Fact 5 Unparking will not dmg or drain your CPU lifespan, think of it this way, they wanted to cheat by making more cores that nothing can use and were cheating by making them useable in other methods.
Goal 1 The reason to try this in the first place isn't really to see an FPS increase, it's for load times.
Bonus If you get more FPS when you unpark cores, but onward to hints,
Hint 1 As above unparking all cores will give more load performance times and maybe slight fps increase in whatever game you may play, the thing of it is, is that windows always will try to use core 1 first and bleed off to another core if it needs to, the reason for unparking the cores is so that if and when windows does need another core its ready to be used instead of being loaded up. Mind you only extreme gamers can actually see a lag on a system when a core is being loaded, 90% of the people in the gaming industry probably would say I'm full of shit but if you played a game so long and you notice something a little faster or slower, they can shovel it.
Hint 2 Another reason for unparking cores is also for some games say World of Warcraft I.E. You can assign cores, some newer games allow that it's also called processor affinity, but you have to know what core you assigning the game to and you have to make sure it is on, again unparking makes sure it's on without a doubt.
Another note to add is say you play the same game with 2 accounts and want both to load up, I.E back to WoW I myself had 2 accounts running at the same time on 2 monitors and with assigning the main account to cores 2 and 3 and the 2nd account to 3 and 4 with everything, it was just a blink of an eye between switching screens and loading was better with unparking the cores.
Goal 2 Unparking the cores is really meant to have them always ready to be used.
So on to cautions
Yeah it will use more power I mentioned before not advisable for laptops
Messing with the windows registry to modify the setting can be risky as Intel uses main and swap cores bla bla bla, its a pain.
All I can say is I hope this helped a little towards what people need, and I take no responsibility if you mess your shit up.