Failed Motherboard Repair In Three Acts

I've never done a motherboard repair, so this is my (bad) attempt at one. I wanted a motherboard that supports both AGP and dual core CPUS for OS development. I found this nForce 3 based thing which was in a vary dirty state. I gave it a good wash, it turns off but powers off/restarts randomly. I suspected the PSU, but it works just fine with another board. Motherboard: MSI K8N Neo2 Platinum, nForce 3 CPU: Athlon 64, Socket 939 GPU: S3 Virde/DX PCI and Radeon 9800 AGP