So I finally got around to ungrading my GFX card, and while it initially started up a few times, it wouldn't fully boot into windows, getting stuck on the windows 10 logo, and once making it to the point that it must have completed installing a windows update.

After that it progressively got shorter into the boot up process with each attempt. On one occasion there were black lines across the whole screen during boot up. Now it won't even post, beep or display anything on screen.

PSU runs
CPU fan runs
HDDs run (yeah I have a bunch of spinning rust)
Mobo SB status light is green
SSD status light is green
GFX fans pulse faster and slower

So far I've tried:

- Replacing CMOS battery
- Resetting CMOS with the jumper
- Using the old GFX card Saphire HD7770 instead of the new RX5500XT
- Removing RAM sticks in case one is bad
- Unplugging all HDDs but my boot SSD drive
- Reseating all power adaptors
- Checked all voltages OK from the PSU (using a wire between green wire and ground so it starts), but not under load.
- Visually inspected Mobo and PSU components for any signs of fried FETs or bulging capacitors.

Could my BIOS have been wiped by not having turned the PC on for two years? Or could I have killed my mobo by using a card that it may not have supported?

PC is fairly ancient! AMD Phenom II 940 in an Asus M4N78 motherboard.

Any ideas on what to do next?

- New PSU
- New Mobo
- Bin it and build a new PC?
- Secret Ninja hack?