RTX 3090, Xid 79: 'GPU has fallen off the bus' fixed by cleaning dust out of PCIe riser

In three linesUser fixes Xid 79 error (GPU fallen off PCIe bus) on RTX 3090 by cleaning dust from PCIe riser connector with brush and 91% isopropyl alcohol. Prior software fixes (power limiting, kernel parameters) had failed.

Summary generated by Claude — human-verified