Beginner‘s Question: How to Perform the Guide While no Display Signal Out?

[Archmage-Cirno]

Thank you so much for the excellent guide! I've got a really dumb question to ask as a beginner: How you guys run gfxutil and perform the following steps when graphic card isn't working? I mean the display should be pitch black as graphic card wasn't supported, so how did you managed to do these steps and retrieved the results without a display? Did you connect the display cable directly to the motherboard or used a supported graphic card to retrieve the results before swapping to the 6900xtxh?

I've changed my graphic card from rx460 to 6900xtxh toxic recently and tried adding agpdmod=pikera, still got a black screen. Then I figured out the xtxh variation should be the cause. Then I found this really detailed guide, but don't no how to perform these steps when I can't see anything on my screen :(

Really appreciate your help and sorry to bother!