So you have questions about 4k gaming? I have some answers.

For Christmas, I received a 55 inch Samsung 4k Curved TV 9000 series, to use as a PC monitor.  To power this beast, I also received a "maxed out" Alienware Area 51 (the new triangular one) with 2 Titan Z's.  Nothing is overclocked yet, but I'll try my best to detail the performance and what to expect when running stuff at 4k. 

4k comes with huge pros, and some pretty bad cons. 

Con - Obviously running at this resolution you're going to need a lot of power.  Can it be done with a single card?  I'm sure it can.  But you will probably have to sacrifice some image quality in games for smoother framerates. 

Con - So far, some games don't seem to "like" this res.  It will take some tweaking in different areas to get it to run just right.  See next point for more detail.

Con - Everything on your screen will need to be smaller.  I say "need" for a reason.   You CAN set Windows (in my case 8.1 pro) to alter the font size to "large", and that will fix pretty much everything.  BUT, for games like Diablo 3 and StarCraft 2, you will lose your mouse, because for some weird reason, Blizzard doesn't support "large font".  You have to set it to medium or smaller then reset your PC if you want to play those games.  PITA.

Con - For some reason, some games don't like "fullscreen" mode at this res.  Some will crash, others won't show anything at all.  Thankfully, usually for those games, there's a setting to run in "fullscreen windowed" mode.  But you're not going to get your "full power" to push the game to it's limits that way either.  Thankfully, that hasn't been much of  problem yet.

Con - You might think, "well if my pc can't handle the resolution, no biggie.  I'll just res down to 1080p like I used to, and all will be fine.  I'll just use the 4k stuff for watching videos, etc." But unfortunately, that might be a bad idea.  I'm still new to using all of this, and still experimenting, but so far, this TV at least, HATES 1080p. It will do it, sure.  But the quality of image goes right down the toilet.  I'm not kidding when I say bad.  This new 4k TV is replacing a 4 yo Samsung 8000 series 1080p TV.  The 4k TV's 1080p is a HUGE downgrade compared to the older TV.  Obviously that's due to native resolutions.  But whatever you do, do not go buy one of these TV's with the intention of using 1080p most of the time.

Con - Not a lot of things scale well to 4k.  Windows, Internet Explorer, and many games are just fine (and incredible - we'll get to that later).  Let's take Tomb Raider as an example.  The game itself looks amazing.  Graphics scale very well.  But the cutscenes which are pre-rendered CGI look like crap.  Blocky, and obviously "magnified" lower res.  It's funny, because before, you'd look to the cutscenes as "benchmarks" for how well the game "could" look if we had advanced in technology enough.  Now, it's like "ahh, it hurts my eyes!  skip it!  skip it!"  All internet images, are "magnified" as well which makes the picture look worse.  The text however is fine, thankfully, due to IE's ability to render the font size accordingly.

Con - The curved TV stuff doesn't seem to make a difference.  It looks "cool", but that's about it.  I had hoped for it being a bit more "immersive" and "surround" my field of view a little more.  It sits on my desk, about 3 feet from me (yes, 55 inches of glory), and I honestly can't tell a difference in my old flat TV as far as "immersion".  However, I still love it (we'll get to that in the pros), so perhaps it does do "something".

Con - Some games experience "input lag".  For example, WoW, has a very slight delay in when a key is pressed or the mouse if moved before it registers onscreen.  This bothered me immensely at first, but I'm getting used to it.  This I believe is due to the TV itself.  But honestly I'm not totally sure, as some games don't experience any at the rate WoW does. 

Con - HDMI 1.0 only supports 30hz at 4k resolution.  Which means that technically, you're going to limit yourself to 30fps when enabling vertical sync (and you're definitely going to have to turn on vert sync because the tearing is quite bad if disabled). 

Ok, enough of the cons.  You're probably going to notice, that the cons list is longer than the pro list.  But I cant stress how impactful the pros are.  They are worth their weight in gold. 

Pro - Holy crap this stuff looks incredible!  I've been using 1080p TV's as PC monitors for about 7 years now.  And going to 4k reminds me of the old DPI arguments we'd get over the old real PC monitors (CRT or LCD).  See, the resolution was technically very high compared to the screen size on those older, smaller displays.  I'm sure the new dedicated pc displays still pump out the same DPI, but you're getting that because of the smaller screen size.  When you keep that res, and increase your screen size up to 40", you're going to sacrifice on DPI a lot.  Text is going to look fuzzy, the quality will go down on everything - at least a bit.  But the 4k TV even at 55 inches brings it all back!  It really does feel like I'm using a GIANT PC monitor. 

Pro - 30hz or not, the games run silky smooth!  I'm sortof confused because I had always thought that 60fps was the standard for smoothness.  But I kid you not, these games are silky.  It's not like playing on a PS3 with a 30fps game.  I honestly do not know how many fps I'm getting from game to game.  I don't use any monitoring software for that.  But they are smooth as hell.

Pro - The colors!  I'm not sure about other TV's, but the Samsung 4k's claim to be able to display 1 billion colors instead of 16.4 million.  You might think, "yeah, but that's only for stuff like 4k movies and crap."  I did too.  Until I booted up WoW in 4k.  I was literally amazed, my wife included.  SOOO many colors, so bright and vivid.  Seriously, just opening my bags, and looking at the inventory and hotkeys is a sight to behold! haha.  The world is of course even better!  Thjs goes for all games, all desktop functions, etc.  I look at my wife's display and her set up (she's using nearly exactly what I was using before the new stuff), and it looks "washed out".  The colors are so drab, on everything.  I'm not kidding.  It's actually pleasing just to sit here and type this message, looking at this smoothness of the text, the deep blacks of "mmorpg.com", and the bright white of the text.  It burns into your retinas lol.

Pro - Speaking of "retina", that's a lot of what it reminds me of.  The Retina display on your iphones and ipads.  Those vivid colors, and pixels you can't detect. 

Pro - Gaming at 4k is beautiful.  So far, the Alienware and Titan Z's have performed very well.  I will be honest though, in some games I have had to turn down the AA and some other things occasionally to retain a smoothness that I prefer.  But it's all been technically playable even maxed out.  I was totally fine with 1080p gaming.  Most everything is setup for that resolution anyway.  But I can see now what I've been missing.  And those of you with normal PC monitors, although much smaller in screensize, know what I mean when I say, it's a lot more crisp.  The graphics are way more defined.  You lose that when you go to a higher screen size.  Not with 4k.  It's back. 

Pro - Obviously, 4k movies and video is amazing.  It's literally the same "jump" in quality we all experienced when we went from 480 TV's to 1080p's.  Only this time, it's even more of a jump.  I can't describe it, so if you don't understand what I mean, go down to your local Best Buy or whatever and go see for yourself.  My TV came with a bundled 1TB external HD filled halfway with pre-loaded movies and documentaries all in 4k.  It's nuts.  My whole family even the little 7 year old can't help but be amazed at how "real" it looks. 

I know the cons list is longer than the pros.  But I cannot stress enough how much the pros still "outweigh" the cons.  We definitely "aren't there yet" however.  GPU's and computing power still isn't enough to warrant the jump yet for the average gamer.  Mine is fine so far, but not many people want to spend 11k on this kind of setup.  I'm guessing it will be a new standard in a couple of years though.  I can't imagine why not.  It's just "better" in so many ways.  If you've been considering the upgrade, I hope this post will help your decision.

If you have any questions, I'd be happy to try and answer them.