No. The i3 6100 will be faster than the Haswell in this compare:
http://www.anandtech.com/bench/product/1497?vs=1197
As said, its not even a competition. Pick the i3.
For gaming with a discrete GPU. The 7870K collapses completely compared to the i3.
I don't see anywhere in there where it says "multitasking"
I suppose that everyone will be doing single threaded particle movement... /sarcasm
There are barely reviews or benchmarks of the two on multitasking scenarios, and the little existent has always been proven as non representative. You have never used both, so you cannot prove it for sure. So get proof, real specific proof,
even if you have to run your own benchmarks of both or just accept that you don't have it and stop regurgitating the same info over and over that sidelines a very specific point I made.
OP,
I proposed the A10-7850K as the difference in performance between it and the A10-7870K is minimal, but the difference in cost already gets you halfway there to a decent 120GB SSD.
I have had the chance to work with both CPUs, an A10-7850K and an i3 (Haswell)
Very few people here can make that claim firsthand. I was quite curious, in fact, excited to see what the i3 could do after reading all that the fanboys write. I was unimpressed with the i3, and the best way to describe the experience would be "temperamental". The A10 always felt smoother. Keep a bunch of browser tabs open, see which one tanks first. And that is not a far fetched scenario of common usage; you are more likely to have facebook, instagram, youtube and a bunch of other things running at the same time, rather than doing single threaded particle movement...
So, the i3 didn't convince me as "the pure awesomeness savior of the CPU world" that many fanboys try to parrot. It didn't felt faster than the A10-7850K, in fact, it felt choppier, but then, even my humble HP Probook 6475b (A10-4600M "trinity" with SSD) has always been described as "faster" than my work machine (Dell Precision M4800, i7 with SSd also) by people who have used both. spreadsheets? open equally fast. PDF annotations? user input is the limiting factor. Folder open equally fast in the HP, and it boots and shutdowns faster.
OP,
My point here is that from your current setup any moder CPU will be a leap forward, and while one might be better than the other, it is not the "very good vs very bad" situation that some are trying to paint. There are benchmarks, but I have always argued that benchmarks are like car loans,
you better read the fine print to understand how those numbers were generated and what they really mean. Maybe that 0.39% interest is per month... The number by PClabs.pl, in either cpu or gpu are always different from the norm, and settings are always vague.
The "better upgrade path" on the blue side is also a myth. Try putting a skylake in a LGA1155 board. Heck, try it on a LGA1150 board, a more modern one, see how much compatibility you got. Beside, most of the times you will be changing motherboard and processor at the same time.