Question Monitor Outputs only when I Swap RAM Slots?

Jun 20, 2020
Hi, recently my computer started playing up with no monitor output and weird GPU fan speeds. Sometimes it kept cycling through boots so after troubleshooting (usual stuff like re-seating and resetting CMOS) I bought some new RAM. Now it will start up only once until I swap my two RAM sticks to 2 of the other 4 RAM slots on my motherboard (GA-Z97X-SLI). I can even restart the computer fine but if I turn it completely off, don't swap the RAM sticks to the unused slots, and turn it back on, it will just boot up, fans spin then stop, and then no monitor output.
I am baffled as to what is going on and hoping it's possibly a BIOS setting I could change on a successful boot or something to fix the problem? Or am I possibly up for a new motherboard?
I would really appreciate any help, thanks.

Specs: GA-Z97X-SLI motherboard, 2 sticks of 8GB Vengeance 1600MHz RAM (new ones), Intel i7 4790 CPU, with a corsair CS640M power supply.
I also have a GTX 970 but have it unplugged currently; when it is plugged in on an unsuccessful boot the fans spin up (I assume max speed as they never usually get fast) and don't stop. Works fine on successful boot.
The Windows RAM diagnostic also says RAM is fine.