True dat, where the devil is Pemalite at?

I'm around, I do need to sleep, eat, work and stuff. :P

Vivster, there are a few games which will take advantage of 6-8 cores, Civilization IV is probably the biggest example, there is a significant reduction in turn times late-game.

Ashes of the Singularity (Supposed to be the game showcasing Direct X 12) there is a fairly decent jump from Quad Cores to Hex to Octo' cores.

If a game is only going to take advantage of 4 cores, then you can run demanding apps beside it with minimal/no performance penalty, say Xsplit, playing back MP3's, whilst transcoding video and more... It's actually one of the few edge cases where AMD's FX chips shine.

Intel's high-end Socket 2011-3 platform will have a longer life as the motherboards are typically built to a higher standard of quality. (My motherboard has a 10 year warranty for example.)
But you pay a stupid amount for that.

If you are not a tech enthusiast, don't care about running a dozen programs alongside your game, then any modern Intel Quad-Core is enough, save your cash and sink it into a better GPU, there are worst ways to go.

My current biggest problem with my CPU (3570k) is that it can't multitask. A single flash Youtube video will rob it of 20-30%. Any current game will bring the CPU to 80% or worse. So doing both at the same time really is no fun. I'll just ask a few questions and hope you can answer them.

I'm seeing CPU performance hits even when I'm limiting the game to 60 fps and then watch a video at te same time. The CPU is at around 70-80% but I'm still seeing stutter ingame. Is that still the cause of the CPU because it only has 4 cores and any additional task will cause latency because the they have to share a core?

If I choose a 6 or 8 core on a game that only uses 4, will the rest of the cores be exclusively used by other programs or will the game try to utilize those somehow too so when I try to multitask I'll see stutter again?

And how does hyperthreading work in this case? Will a 4 core game use all physical cores or only 4 logical cores?

Money isn't the big issue when I decide to go for a 6900k but the real issue would be if it performs only the same or even worse because it's much lower clocked than a 6700k.

This is my current preliminary setup. One with 6700k and one with 6900k

https://geizhals.de/?cat=WL-706194

https://geizhals.de/?cat=WL-709234

Vivster, why are you dropping so much into the mobo? Mind you, I'm clueless but afaik, if you don't intend to overclock, there is practically no benefit to a motherboard like that, aside from some added ports.

Most of the cost is 2 electric PCIEx16 slots for SLI and support for high clocked DDR4. If you want both, the selection becomes pretty thin. In fact  the Z170-WS is the only ASUS board that has 2x PCIex16. Also, I won't compromise on a non-ASUS mainboard.

You have to understand that this is my next big build, I only do those every 3 years or so. Which means all parts will have to be premium. I'd rather pay 1000€ too much than live 3 years with the thought that I could've gotten something better. You know, like I did with my current build.

Flash video shouldn't use any CPU time, it should be hardware accellerated these days.
The Ivy-Bridge based i5 3570K is still pretty potent, I would overclock it and just drop in a new GPU personally, sometimes though, you get the upgrade itch and you just gotta' upgrade. - Nothing really beats the smell of fresh shiny new hardware in the morning. lol

The stutter could be caused by anything, I have even seen cheap TLC NAND drives cause a system to crumple when multi-tasking, I have seen Speed Step be the cause of it as the CPU ramps up and down in clock speed... And I have seen games end up improperly allocated to the wrong CPU threads and thus end up sharing the resources of 1 CPU core between 2 threads.

What you could do is open up task manager and by right clicking on the processes tab, find the game's process and set it's affinity to 2-3 of your CPU threads/cores, that will limit the game just to a pair of CPU cores. Then do the same for your web browser+flash for the spare cores.
See if it makes everything hum along better, you might need to experiment.

As for your CPU core question, If you chose a 6-8 core CPU and a game is using 4 cores, then you will have 2-4 cores idle/doing minimal work, maybe doing some background windows stuff at most, unless you also load it down with extra programs.
Windows will typically allocate everything fairly intelligently though, even juggle things around.

Hyper Threading is where a single CPU core pretends it's "two" CPU cores, by using some of it's spare/idle resources in the CPU cores pipeline to start working on the second thread.
Hyper Threading is great if you need it, but it's not a replacement for real cores... And in some rare cases can even decrease performance.

One thing to keep in mind is that the big socket 2011-3 is a CPU architecture behind Intels Mainstream lineup, which means single-core performance is slightly lesser (Usually made up for the increase in cache), but thanks to the extra CPU cores you should find that the platform will last you allot longer.

If you were to compare your Ivy Bridge Chip against Intel's newer CPU's at the same clock and core count you are looking at roughly a 20% performance increase in favor of Intels newer chips.
Or... To put it another way... Your CPU at 4.0 - 4.1Ghz would be roughly equivalent to a stock Core i5 6600.

Thanks for the answers.

I tried to overclock my CPU once and even though I followed the instructions carefully it didn't end well and I had to reset the BIOS. I'm not too keen to try it again if I don't have to. The thing is that I will definitely need a new mainboard anyway because it's toast after the recent PSU desaster.

I've been planning to update my PC since last year and wanted to do it once Kaby Lake drops but I don't really have that much choice now. But I have no problem plunging now. I will carry over my 980ti in hopes that it's just the MB and not also the card that's busted.

My current mood tells me to get this setup. http://geizhals.de/?cat=WL-709234

The other option would be to compromise and save 400€ with a 6850k over a 6900k. I'm really at a loss here and I want to order asap.

My personal opinion is that the 6900K is a waste of money, the 6850K is much better value.
If you don't need the PCI-E lanes the 6800 is better again. - The limited PCI-E lanes only becomes an issue if you go beyond 2 GPU's. Or some edge-case Compute scenario's.

I have had a 6 Core processor for 6 years since AMD dropped the Phenom 2 x6 1090T, then moved to the 3930K after that... Software really isn't pushing past 6 cores right now, so you will be tickled pink with either the Hex or the Octo.

Guess I'll go with the 6850k then. The price increase from the 6800k is not big enough to not go for it.

http://geizhals.de/?cat=WL-709234

So this'll be my final setup. I hope I can have it all together by the end of next week.