Welp, sadly it seems that the Chaintech 5IFM 430HX board is dead 🙁
No POST, tested with anything I could think of - different SIMMs, different CPUs (P166 standard, P133, P233MMX, Cyrix 6x86) and even different PSUs. None would get a POST or beeps out of it.
At least the GPUs (GTX 1050 2GB without 6pin PCI-E, XFX HD7970 3GB w/ missing fans) both work, and one has already been cleaned (GTX1050). Waiting on ordering a parts card for the other one. That, or getting a different heatsink altogether. (I don't mind the slightest slapping a MSI or a Sapphire cooler on it, as long as it can use the 4pin fan header that's on the XFX.)
"Enter at your own peril, past the bolted door..."
Main PC: i5 3470, GB B75M-D3H, 16GB RAM, 2x1TB
98SE : P3 650, Soyo SY-6BA+IV, 384MB RAM, 80GB