Help! M3420 won't turn on with new graphics card, tried everything

Hello!

I can't get my M3420 to boot with any graphics card other than the OEM. Currently I am trying an RX470 Radeon. I have upgraded the power supply, and the PCIe cable is working and correctly connected to the card. Card seats nicely in the PCIe slot. BIOS is latest, and all settings were restored to "Optimized Default". (Note: There is no graphics port on the mobo.) I do not even get anything whatsoever on the monitor--not the ACER splash screen, nor the boot options scree/BIOS screen. Just a black monitor with no signal--green light on monitor does not come on. The blue light on the tower comes on for about five seconds, then shuts off. Fans are still running, and I need to hold down the power button for about eight seconds before the fans power down. Do I need to let it sit for a while with fans running so it "sorts things out"? I don't think it's a driver problem, but it's not impossible. Do I need to uninstall the existing AMD drivers even though the new card is also AMD Radeon? Truly need help ASAP on this, folks. Please?

Les

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billsey

How much memory is on the new card?

poliwog

Seems to be a BIOS issue. Cards want UEFI bit the motherboard doesn't support it.

billsey

Yeah, there's a window between BIOS and UEFI that breaks some graphics cards. Check to make sure there isn't a firmware update for the card to allow BIOS boot.