Only long beep tones with a few seconds pauses

Depending on the beeps, you are looking at usually memory or video card error. first step is to remove the memory from the system and place only one stick in at a time. if the unit only has one stick then you need to get a known workign stick to test with. if the known working stick works or only one of the other sticks work then check each of the slots indvidually. if you find that the unit does not boot with the memory in a specific slot, then you have a bad motherboard. if the unit boots in every slot with the good memory, then you have a bad stick. If the pc boots after pulling and reseating the memory, you got one of the rare issues of a memory stick lossening up. If nothing boots it, then you need to move on to either the video card or motherboard.

Without the exact beeps and length of each beep i could not give you more than a generalized answer.