These are fairly classic symptoms but they may not present obviously enough early on.
I had a power supply issue with my old Corsair CX430 (430 Watt).
The build had two old 95W Xeon CPUs, 2 USB devices and a PCI-E powered Nvidia Quadro or at one point a GT710. This shouldn't have overwhelmed the PS but this power supply is known to be weak by many users.
Symptom 1. Graphics Issues
This would only present it self after coming back with the........
I backed up everything in the /mnt/sd_card directory thinking that some dataloss could occur for some reason but purposely left my microSDHC unbacked up thinking that "it won't touch that since it's external" and Samsung's and other manufacturers website even say this (that it won't be affected and not to worry etc).
Apparently I was wrong, my microSD was "undetected" and asked to be formatted after the upgrade (there goes 3-months worth of family photos). No........