I have a PC with a single GTX 970. I bought another GTA 970 for SLI, my CPU, PSU and Motherboard are compatible, i7 4790k, 1000W 80+ platinum, gigabyte z97x ud3h. I plugged in the cards to the x16 slot and x8 slot and plugged in the bridge. Drivers detect both cards, but won't let me turn on SLI because they don't see the bridge. Then I shut down and tried another bridge, because one came with motherboard, one came with new graphics card. Same thing. I then tried the other SLI bridge pluging thingy, nope, then I ran Display Driver Uninstaller and reinstalled my drivers. Same thing. I'm out of ideas, how can I get SLI working?
Nvidia Control Panel shows both cards, but will not let me enable SLI, it says: "To maximize 3D performance, connect the SLI-ready graphics cards with an SLI connector." But the bridge is plugged in. And I've tried more than one in each space on the cards.