I presume that the speaker is connected to the motherboard and no beeps are heard. The problem sounds to me like either the processor is faulty or not fitted properly or the memory may be badly installed or faulty. If the graphics card wasn't installed properly you'd get some beeps from the speaker.
Remove the memory and reinstall it ensuring that its in the right slot (most motherboards have 2 or 3 slots for memory and it does make a difference which slot you use). If that makes no difference then if you have another computer available borrow the memory from that and try it in your board. If that doesn't work then it may be the CPU. I'm sure some of the others will come up with ideas as well. Good luck