Try accessing the BIOS by tapping/holding down the DELETE key as the PC is starting.
As an alternative to running Memtest try this -
If you have more than one stick of memory remove all but one stick of memory, try rotating through each stick.
Try one stick of memory in each slot.
If you're able to get the computer to boot with one or more of the sticks of memory it's likely you're dealing with some bad memory. Try to identify what stick of memory is bad and replace it.