I'm running Win7 64 on one of the first generation ASUS MBs for the i2600k without overclocking. I added an EVGA 1070 and run with everything maxed out on a 1920x1080 Viewsonic monitor. I can't see any difference with the Envirnmental slider so I dialed it back to 1 but either way I am getting the max, 60 fps everywhere all the time. Like everyone else, the game stumbles but it isn't our hardware.
This is a PCIe2 chip/MB handicap, and PCIe3.x will take a new processor and MB. I see no need to upgrade further.
As you've been warned, the same card by any of the manufactures can be wildly different with less memory, backplate or fans. Avoid the Founder's editions, the tech has moved on.
For general info on card comparisons, see
http://www.cpubenchmark.net/Suppose you buy a 1060. You might find out that it has half the GDR5 memory for models withing the same manufacture. It might not have a backplate, or be under clocked relative to newer models. This has happened and it's a hard lesson when $30.xx more might buy the top card in someone else's line.
That link went to the CPU page, here's the Video Card page:
http://www.videocardbenchmark.net/