My first build was in 1985. I built a clone of an IBM XT. Where the IBM machine used an Intel 8088-5 CPU running at 4.77Mhz, I used a NEC V20-10 running at 8Mhz. The CPU was installed in a Taiwanese no-name motherboard. Most computers back then used Monochrome Display Adapter (MDA) video cards that could display text only, no graphics. I opted to go with a Color Graphics Adapter (CGA) video card that could display text and graphics (4 of the ugliest colors imaginable).
When I completed the build and attempted to boot for the first time, no video showed on the display. I took the motherboard back where I bought it. The owner told me that the problem was that I didn't have the motherboard switches set correctly. He installed a MDA card, set the switches to monochrome, attached a monochrome display and it booted right up. I insisted that he show me it working with a CGA adapter installed. He didn't want to do it, claiming it was a waste of time. I insisted, so he finally installed a CGA adapter, set the switches to color, attached a color display and - no video. BTW, computers back then didn't use CMOS to store computer settings as modern computers do, you had to set switches on the MB to indicate things like how much memory was installed, color/mono video, how many floppy drives, etc...
At this time he grabbed the phone and jabbered in Chinese to someone on the other end. After he hung up, he told me to go away and come back in 1 hour. I left for an hour and when I returned, the board was working correctly with a color monitor! Apparently in that 1 hour, whomever he called on the phone, made corrections to the ERSO (Taiwanese) BIOS and the new BIOS was burned and installed on the board. Apparently, I was the first to ever attempt a build with a CGA video adapter with that MB/BIOS combo. At any rate, I was now happy as my first build was fully functional and overall it was a positive experience.