After a couple of failed attempts at booting up a newly built system, I discovered that the 4-pin CPU fan header on my Gigabyte UD4P seems to be broken. When powering on, the fan on my CM Hyper 212 Plus will spin once and then lose power. I tried connecting the same fan to the 4-pin SYS_FAN2 header and that worked just fine. Unfortunately, the system still hangs and refuses to boot. No video, no beeps, and the optical drive keeps searching repetitively (I inserted the mobo driver disc to no effect).
I also noticed that all four if the board's "Phase LEDs" light up as soon as I power on, which indicates maximum CPU load. I have no idea if this normal or not; Gigabyte documentation explains nothing.
I am thinking that best case scenario, the system recognizes that the CPU fan header is disconnected/broken and refuses to boot up without an active CPU cooler (even though it is active, just on the SYS_FAN2 header). Worst case scenario, the CPU has been permanently damaged when I first powered up the system with the CPU cooler connected to the defunct CPU fan header (I was staring at the screen and looking around for about 30 seconds before realizing the CPU cooler fan was not spinning).
If anyone has any thoughts or can confirm any of my suspicions, I would be much obliged. I have already contacted Newegg and Gigabyte support, but it being the weekend I'm not expecting any help for the next few days.