There are a handful of games that benefit from hyper-threading in the i7, like Battlefield 3 & 4, however getting a better graphics card is almost always the cheapest way to get a jump in performance. Especially because most games do not support hyper-threading.

Type 4670k vs 4770k into a search engine to get fps comparisons, etc. You'll be able to see nice graphs of the negligible difference in gaming performance versus the big difference in rendering/editing performance.

Well, quite the reverse imho

Basically, the i7 adds 33% more cache and hyperthreading to the i5. For video edition and a very limited number of applications and games, the ability to emulate 8 cores makes some difference. But for the largest number, the 4 cores are more than sufficient and you may want to prfer a better GPU or more RAM to a more powerful CPU

Moreover, unless you want to overclock, CPUs ending with a k ( 4670k/4770k) add nothing to their regular counterpart (4670/4770)

If it's cost effectiveness you're after, you could even consider the i5 4570. It's only marginally less powerful than the 4670 but less expensive (170€ vs 200€) . The 4440 is only marginally less expensive than the 4570 ( 165€) but the performance gap is about the same as between the 4670 and the 4570. To make it simple :

a 4440 is 3% cheaper than a 4570 , but offers 8% less performance
a 4570 is 10% cheaper than a 4670 , but offers 6% less performance
a 4670 is 33% cheaper than a 4770, offers 3% to 18% less performance, depending on the application

edit : hadn't read the table correctly. In single thread apps a 4770 i7 is 3% faster than a 4670 i5 , not 1%

Geez, why does these things have to have so many variables :D

So the general consensus is that i5 is enough for gaming today? What about the next few years?

It will be enough, and when its not enough, the i7 wouldnt be enough, too. Problem is, the new nextgen consoles have lower specs than high end PCs and most games will be for all of them.
If you really want to go for the 8 Threads design and hope for games using that many without getting problems, you could think of a Xeon 1230v3 which is an i7 without the graphics which you wont need anyway and i think 100 MHz less ... but alot cheaper.
For better graphics still higher videocard is the better investment :P

My feeling is that the rythm of evolution has slowed down. My i7 870 is still more than enough to deliver a plasant experience in Shogun 2 TW ( but has seen its RAM upgraded to 16 gb, its GPU changed and has benefited from the addition of an SSD)

Besides this, if you wanted something more powerful, you'd have to go for a Xeon or an Ivy-E. Then, yes, you'd have a 6 core with hyperthreading, delivering 50% more raw performance than the i5 4570 ... with a TDP of 130W, the need for a new PSU and cooling solution, at a price of about 1000€ (i7 4960X) for the CPU alone or its little brother around 600€ (i7 4930k ). But by the time you actually need that expensive reserve of performance, you'll probably have the opportunity to achieve even better results with a newer CPU and GPU

My advice would be : why spend more than what you have to ?

For Xeon processors, it's worth noting that socket 1366 and 2011 motherboards are quite expensive.
That leaves indeed the Xeon E3 1230 and 1240 that will perform on par with an i7 and remain within the 400€ budget for CPU+MB. But they are not more / not less futureproof than the Haswells, i5 or i7

Just suggested if he wanted 8 threads one could get those instead of the more expensive i7 4770. The 1240v3 more or less is the same as i7 4770, just 20€ less, the 1230v3 has afaik 100MHz less, but is 50€ cheaper, so pricewise gets nearer to the i5. As all of them use the same socket 1150, they use the most modern Intel infrastructure.
For normal people socket 1366 and 2011 dont really make sense, especially as their old chipset is very long outdated ;)

Part of the beauty of this site is that i can find enough old games to keep me going and i never have to upgrade my computer!

Although Galactic civilizations 3 is coming soon - it is the one new game i would buy a new computer for! But so far my computer does have the minimum requirements including 64 bit operating system which i had the good sense to order with my old computer when i bought it five years ago. But if the game does not run well i will be upgrading.

I just remembered the last time i upgraded my computer, i did that for a single game as well - X3!

The point is, i never upgrade just because my computer is old, i upgrade when i have a specific need to do so.

Edit: oh and the word 'upgrade' is one that has not truly applied to my new systems ever since the Pentium 2 was released and they started that shit where old parts are not compatible, even the power supply! But at least i can still connect my old HDD and DVD dive.... oh wait, now IDE is vanishing too! I can appreciate improvements in technology, but before the pentuim 2 it was not like that at all, you could interchange parts from computers with a significant age difference... improvements in technology are good, but flexibility for poor working class asseholes like me is better!

Okay, let's revive this. I think my motherboard is dying, as the computer actually managed to lose a hard drive while it was on, never happened before.

Anyway, let's make a deal. Suggest me a good combination of processor & motherboard, and if I end up getting that, you'll get a 9.99 gog for it.

Budget is still 400 euro for those.

Together with the stock cooler which you will get when buying the boxed version) t will run fine and with good "tuning" will even be unhearable in most desktop things.
As motherboard f you dont want to go SLI or Crossfire with two video cards i would prefer the H87 chipset, for me it would be Asrock H87 pro4, cheap and good. For CPU you can look at the mentioned Xeon 1230v3 or 1240v3 if you want 8 threads at once, but the i5 is a good choice, too :)

Do you overclock?

Stuck with the old ATX size and not daring enough to enter the small world of ITX? :)

If youre looking for most powerful intel cpu with overclocking capability -> I7-4770K. If you dont OC, then Xeon E3-1230V3. Then there is one computer shop in Jyväskylä that seems to sell 4770K at Huuto.net at almost the same price (230€ or so) every now and then.
Its not as much about heat as about noise. If you can stand the noise, stock is "sort of ok" - but they are really the bare minium. What case youre using? Mobo and case can put some restrictions on coolers.

I'll just repeat what I said on the first page ;)

At the moment I am looking at these
http://www.jimms.fi/tuote/Z87-G45-GAMING (z87-G45 mobo)
http://www.jimms.fi/tuote/BX80646I54570 (Haswell i5-4570 processor)
http://www.jimms.fi/tuote/RC-942-KKN1 (Coolermaster Case)

only go for the K of intel if you plan to overclock if not dont pick them, they are a little more expensive just for that.

i5 vs i7 is all about the extra threads for multitasking maybe in the future this will be used in games right now they are not but they are very handy for just using your pc, encoding videos, multitasking, compressing and uncompressing files etc etc