So I'm probably dealing with a dead motherboard - specifically, a Biostar H77MU3 - but I've never seen one fail this way
before, and I've been building PCs since 1996. The story follows.
I put together a little box to use as a workstation / computational node for working with seismic data, separate from my main rig. It sports an i5 3570K, 16 gigs of DDR3-1600, and the aforementioned motherboard, along with a Rosewill PCIe wireless NIC, a plain vanilla HIS Radeon 7850, and a brand new SeaSonic 620W power supply. I tried to boot a BunsenLabs flash drive, which complained it couldn't set a valid video mode. I yanked the Radeon and used the IGP. It still bitched about an invalid video mode, so I switched to a Xubuntu flash drive and that worked without a hitch. Swapped the Radeon back in, had no issues, updated the system... and suddenly the wireless card didn't work any more. Tried disabling it to force a firmware reload, rebooted, tried to re-enable, and the Additional Drivers dialog insisted that the hardware wasn't working. Then I shut it down to take the Radeon out... and it all went to hell. Tutti Frutti hell.
Forgive the poor focus of the image, but it flashes this gibberish for one second, turns the signal off, and repeats in an endless loop. My iPhone had trouble keeping up. I don't have a buzzer or PC speaker installed, but removing the RAM results in a black screen, so something during POST is failing between initial RAM identification and display init. Because no good deed goes unpunished, I took it all apart to make sure nothing was shorting against the motherboard, put it back together... and now it doesn't power on at all. I suspect the latter may have something to do with my using a magnetic screwdriver to take out the screws - forgive me, it was late and I was tired - so maybe, with fingers crossed, it'll at least power on after I put my kids to bed tonight.
I'm kind of at a loss. Any advice is greatly appreciated.
Media: Core i9 7940x, 32 gigs RAM, GTX Titan Xm, Win10 Pro
Science: Ryzen 7 1700, 16 gigs RAM, RX Vega 56, Xubuntu 18.04
Server: Xeon E5-4640, 32 gigs ECC RAM, FirePro V8800, Win10 Pro
Read my words at https://www.wallabyjones.com/