Populated RAM sockets and soldered a motherboard mod on a Tandy Color Computer in 1986-1987; upgraded and built my own PC hardware since 1987, from 8088/XT to 80286, 80386, 80486SX, Pentium-class, to current Core2Quad; also have still-running 1997-vintage Pentium II laptop and 2003 Athlon XP 2000+ tower (Linux is great for older hardware; I don't run any version of Windows on my own machines any more).
I don't understand electronics (transistors and chips are magic!), but I'm pretty good at plugging stuff in the correct way and figuring out what's failed based on symptoms.