No bios post at 75Hz

Hi All,

   It has been at over 7 years since I last built a machine and a lot has changed since then! I have just built a machine with these specs:

CPU - AMD Ryzen 5 3400G Processor (4C/8T, 6 MB cache, 4.2 GHz Max Boost) with Radeon RX Vega 11 Graphics
Gfx - Gigabyte Radeon RX 5600 XT Gaming OC 6GB GDDR6 Graphics Card
Motherboard - Asrock X470 Master SLI
PSU - Thermaltake TPG-0750F-R 750W Toughpower Grand RGB 750W 80Plus Gold PC- power adapter
Memory - G.Skill DIMM 16GB DDR4-3200 Kit, RAM
Case - SaharaGaming C500B ATX Black Tempered Glasses gaming case
Monitors - 3 x dell se2717h

My monitors are all connected with a display port to hdmi adapter and work just fine. However I cannot access the bios on these monitors. I believe this is because they only run at 75hz and the bios can only handle 60hz.

I have flashed the bios with the latest version. I have been able to get into the bios by connecting a very very old monitor to it. This does not work as a final solution for me as I am dual booting windows 10 and ubuntu but as I cannot access anything until the graphic drivers kickin I cannot see the boot menu.

Does anyone know if there is a solution to this? Or do I need to return the motherboard and get a different make or model?

Thanks

Hey cx5 thanks for the response

cx5 wrote: I think the priority has gone to build-in GPU from the 3400G APU. So if you want to display from your powerful 5600XT, then must set bios graphics priority to PCIE-1 I think, or something like that. In fact I could not help myself but to recommend you sell the 3400G APU away and buy a pure CPU only without build in GPU, for around same price I think the new Ryzen 3300x or up $20 for Ryzen 3600, because you have such a nice 5600XT dedicated GPU To match the 5600XT it to 3400G is a waste of either build in GPU or the 5600XT.

Just checked the bios and the onboard gfx card is disabled so surely it cannot be that? Also on the 5600XT if I connect the ancient monitor to display port 3 then I can access the bios no bother so it seems to me the old monitor does 60Hz and the new ones only 75Hz..... that seems to be a crux of the problem to me or am I missing something?

As for selling my CPU, things have changed so much since I last built a PC and I haven't gamed for probably over 10 years. It never entered my head I was duplicating resources which now that I think about it was a waste of money..... However would it actually worth selling my CPU second hand and buying another one, wouldn't I just lose more money because the CPU is second hand?

Thanks again for replying

Squiggley