I had a GFX card that would only work when warm (power-on PC, black screen, wait 30 seconds, power-off PC, power-on PC, PC boots). Failing to wait long enough t

I had a GFX card that would only work when warm (power-on PC, black screen, wait 30 seconds, power-off PC, power-on PC, PC boots). Failing to wait long enough the PC wouldn't boot. PC booted fine with another GFX card. Never tried debugging further. My wife had a computer (before we met) that would boot only when warmed up using a hair dryer !