No picture (black) screen after changing graphics card

[coypuppy]

I built a new Ryzen+ machine with 2700X and the Gigabyte Aorus 7 WiFi motherboard a month ago. I used an old but still decent Gigabyte NVidia 670 GPU (this is not primarily a gaming PC, just some light/moderate gaming) with the intention of replacing it with a Zotac 780 (Ti?) which was in my previous main machine. After replacing the card, there is no picture on the screen whatsoever. I tried HDMI instead of display port, I tried BIOS reset but there's never any picture (no boot screen, nothing). I believe the machine does boot to Windows based on HDD lights and bios diagnostic motherboard LED screen. I tried switching several times, 670 always works, 780 never. There is nothing wrong with 780 as it works fine when I put it back in the old PC (on different monitor though - but it used to work on the first monitor too, for years). The monitor is a Samsung 3440x1440 21:9 ultrawide. PSU is a Seasonic Gold, can't recall the power but it's at least 550W so it shouldn't be a problem, especially just for boot. I googled but couldn't find any suggestions that would seem to apply to my case. Any ideas?

 

[xeriian]

I'm not an expert but after replacing my R9 270x 2GB over the weekend with my new GTX 1070 I had issues with getting my display to come on.
After searching the web for ideas and not finding crap I decided to unplug my HDMI and power cord from my monitor as well as my HDMI and power to my computer let it sit for 30 seconds plugged them back in botted my computer and BAM it came on. Let me know if that worked for you.

 

[coypuppy]

No, that didn't help. However, moving the card to another PCIE slot - a lower, 8X slot (instead of top 16X) has actually "solved" the problem. That makes no sense to me - the slot is fine with 670, I cannot imagine it's defective. The only thing I might try is to manually set the PCIE generation in BIOS, in case the card is not recognized. It has to be some kind of compatibility issue.