My friend has been telling me about keyboards and their inability to deal with 3 simultaneous inputs. Seems the mechanical ones have no problems and very few of the normal/gaming/laptop ones are able to do this.
To test:
Push down both left and right shift keys and type "the quick brown fox jumps right over the lazy dog"
Depending on how many letters are missing, you can judge the quality of the keyboard.
THE QUICK BROWN FOX JUMPS RIGHT OVER THE LAZY DOG.
Keyboard: Logitech G15 v1