I have a Evga GeForce 560 in my computer right now. My motherboard has multiple slots to hook graphics cards into so I figure I could go out and buy a PNY GeForce 960 and put it in. I got a PCI cable that didn't come with my power supply (Is this where my problem is?) to hook up power from my Corsair HX1000 power supply. I've read that My power supply is big enough to run both cards so I hooked up the SLI adapter. It doesn't seem to work though.
I've been able to just run off the 560 with my 960 plugged in on the motherboard, but didn't have a PCI cable yet. I did that for about 2 weeks and it ran fine. Didn't notice a jump in frame rates, but nothing seemed to be breaking or acting funny too.
Do I just need to bite the bullet and get another 960? Or would it be worth it to get another 560 and attempt SLI with the 560's? Any tips, tricks, or advice would be much appreciated.