I am using an older motherboard, a Gigabyte GA-B75M-D3H and in March I removed my Radeon HD 6970 and replaced with an MSI Ventus 3x Geforce RTX 3070 in order to see if I could mine ETH. After powering on the computer it did not allow me to go back into the BIOS by hitting the delete key on the keyboard - no message displayed so I had to make sure my BIOS was properly configured without this GPU installed (I configured to use on-board video instead of auto detect). After about 10 seconds of being powered up with a blank/black screen (no signal being provided to the monitor), the system rebooted again. I had to wait about a minute before the system would actually display my login and the desktop. After that I was able to overclock the GPU using MSI Afterburner and bring up a browser to monitor the mining progress. I have rebooted several times since March and it boots fine... no rebooting, no dark screens with no signal, etc. I am expanding my crypto mining and assumed I could put two GPUs on this board and was able to obtain and AMD Gigabyte Radeon RX 6700 XT yesterday. After installing the GPU and upon booting up, the system did the same thing.... booted up, no way to hit a key to get into the BIOS, it rebooted twice maintaining a completely dark screen... and then nothing. I removed the 6700 XT and rebooted only with the RTX 3070. Once again, it booted and displayed a dark screen and after about 10 seconds it rebooted again, after about a minute the login screen presented itself and the computer is running fine. I rebooted again and this time no dark screen; it went straight into the long in screen. FYI, I am running window10 professional and before the 3070 installation I set the BIOS to use the onboard video instead of a GPU - autodetect seemed to be defaulting to the GPU. I also have a Corsair 850 watt gold series power supply so I know power isn't an issue. Has anyone run into similar issues or have a suggestion as to what might fix this? Also curious about the double reboot when it appears the motherboard "sees" a different configuration. Do I need to be more patient with two GPUs installed?