No ram = no power on
nevermind boot, with no ram installed, the motherboard will not turn on. Well it will but nothing will happen. If you the case speaker attached, then you will hear some beeps.
To test ram, install in working system.
Take out all known working ram and put 1 stick of suspected faulty ram in working comp. If it boots, if it doesnt boot, then try in next ram slot, till theres no more ram slots to use. Still not working? That ram stick is definately faulty! If, however, the comp boots, use mem test cd to test the ram stick fully.
Do the above for all of the ram sticks you suspect faulty.