Dell Dim 4300s ram upgrade

I upgraded the ram on my Dell Dim 4300s from 133mhz to 1gb (2 512mb). When I turn the PC on all it does is beep and the monitor shows no signal.Software is windows XP

I think it beeps 3 or 4 times then repeats

Thanks 4 for help, This is the PC my special ed students use 🙁
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