That is a very un-scientific way of checking thye RAM as it does not take into consideration the quality of the socket it is inserted into or if your insertion was done properly. However if you have then checked the suspect stick in another machine and the same faults are there, then I would be inclined to accept the failure of the memory.

If the video doesn't work then you may have too much RAM assigned to the on-board Video, this should be correctable by resetting the BIOS by disconnecting the machine from the mains supply, removing the internal battery and using the BIOS/CMOS reset jumper on the motherboard.

Good Luck