U3 like U4 was built with the then existing technology a few years back. Technology, techniques etc. has moved waaaay past that now. So U4 adds all those extra nice things you see in the demo. Some things could obviously not be implemented into the existing engine. And if the change is big enough it warrants a new number.

In this case the change is definitely big enough. But that doesnt mean it wont scale down...

I realise that, but what I was saying is that a developer has to buy the engine. It will be cheaper to buy the U3 engine rather than the U4 engine, and if you are not going to use the new features of U4, why bother paying for it?

It makes no sense to spend money unnecessarily, hence my presumption that if a dev buys U4, they will use the new features.

But anyway, back to the question; specs needed to run a maxed out U4 engine game, so we're talking DX 11.1, particle affects galore, destructible scenery, full on liquids, and huge draw distances ^^

I would guess a top eng i5, poss 16GB DDR3, gtx 680 or gtx 760 (?) +

I'm sure you already know the things I'm about to type but I kind of want to bring some points to people's attention as well. When you are building a PC that's general purpose including gaming, you really need to consider a few things:

1.) How long will these parts last me?

2.) What kind of warranty will I have on these parts?

3.) How future proof will my build be in x amount of years?

4.) Bottleneck?

Point 1:

YOU NEVER CHEAP OUT ON A PSU FROM SOME RANDOM COMPANY! I can't stress how important it is to get PSUs from known name brands that have some sort of 80+ label on it(and stay the fuck away from Rosewill ones). A shit PSU will burn out a little after your warranty goes out because they are designed that way and it's an added cost, trust me, that holds true 100% of the time.

Same way with motherboards, DONOT BUY FROM SHIT COMPANIES! Like Biostar is a pile of shit, Foxconn you stay the hell away from, MSI you have to check what kind of board because some use really shitty capacitors and you will have boot problems in like 1-2 years. Asrock used to suck in the early 2000's but they are now very good. Asus is also decent since they have high performance. Gigabyte is a stable company, they are right in the middle, not good nor bad but gets the job done.

RAM, G.Skill or Corsair(both life time warranty obviously, G.Skill RMA is damn fast), only go Kingston when you really have no choice since I've hated them since day 1 because while people praised it, I know the pieces of shit they really are....... I gave them my middle finger from day 1.

Rest of the parts generally last a long time so whatever. HDD is hit and miss and you can't do much about that(It's a matured tech, so you score or you die.) SSD, well, go for MLC type, they last longer, TLC is okay though if it's like, for your mom even though it doesn't last as long, SLC costs a shit ton so yeah.......

Point 2:

I don't need to explain this, warranty is important and everybody knows this, always check!

Point 3:

You might be spending less money now, but if you have to constantly update it, then you end up spending the same amount or more depending on what you want to do with your device. The truth is that weak hardware will require more constant updates if you want to game on it unlike non-gaming machines. You need to plan it out.

Point 4:

Fuck..... I have seen so many people building PCs that are bottlenecked to shit or using bad parts, if you look at my build(from this thread, not my sig), that's about as balanced as you are going to get and you can still do general purpose on it since it has 1TB of HDD space.

And that's all, cheap isn't everything, consult experts from good PC building sites or forums if you have to, think about if you want to OC, heat dissipattion and all that, constantly hunt for good deals, Gaming PC building and upkeep is like Nascar, you are always going to be tuning it, I mean shit I'm still tuning mine still and I've gone from like 44 Average FPS in Tomb Raider with most things maxed 1080p(only thing not maxed is AA set to FXAA) to like 62 Average FPS now with same settings by just fucking around with the GPU.

"Lifetime Warranty" is usually a warranty for as long as the product is on the market, not your actuall lifetime. - So the warranty might end up only being days... Or it could be a decade from when you purchased it, don't let it influence your buying decision.

But to add to that... Patriot, Samsung Eco green are great too. - Also fun fact, Heat sinks on Ram do nothing, don't let it influence your buying decision unless colour/style is important.

Here is the thing about Bottlenecks, it's impossible to get rid of them and In a grand world where everything was fair and fantastic... A game/program would require equal amounts of processing time from the GPU and CPU.
Unfortunatly, it doesn't work like that in the real world, some games/programs require more from your processor or more from your graphics card and that can even change on the fly while you're running said game.

Take Battlefield 3 for example... If you play the games single player campaign, the bottleneck is going to be your graphics card as even a 5-7 year old dual-core processor can run it *very* well.
Fire up a 64 player multiplayer game with loads of vehicles, explosions and people going on, the load quickly moves from the graphics card to the processor, here even a 6 core processor will shine.

Also. Everyone should have an SSD, even your grandmother, it's the best way to make a PC feel fast and responsive.

I RMA'ed  a stick to G.Skill and they just gave me a different model with the same spec lol, so yeah I know what you mean.  I mentioned those because they have good prices while being reliable :D

Like you said, bottleneck is a funny thing, I aim for all around personally, and that comes with experience I guess.

On cheap builds people'd have to opt for TLC SSDs, they can be very affordable since I did get my mom a 120GB for 80 bucks not that long ago(Samsung 840.)

The FAR CRY 3 build I made easily could.  

Putting in a 7970 for Far Cry 3, a multiplatform game was a little bit overkill wasn't it?

It had a 7850 and costed $500.