Wait, so that's what happens:
Screen A+B = bad connection
Screen A only = good connection
What if you only run monitor B? If the connection goes bad with only B running, this could be due to a badly shielded cable. Try B with A's cables then to verify. Swap and test both power and signal cable one by one.
Yes, the WiFi card is the other card there is, right below the GPU, the one with the antennas. I mean it has antennas, right? Not just empty plugs on the outside?
FWIW judging by this pic, the white connector doesn't look like a standard molex (ie. power) connector, so missing power is not the issue either with the card, as I suspected.
edit: You have a decent and sufficiently powerful (for your current hardware) PSU then, that's good to know. It's probably way more reliable than the no-name 500W from the spec sheet.
Last edited by Baobhan-Sith; 02-27-2017 at 07:30 PM.