I got the Dell screen then the black screen nothing happened after that. Tech support instructed me to hit some keys? then I got a diagnostic screen with 3 contiuous beeps three times then 3 single beeps. I was told it's a motherboard problem.

Can anyone tell me exactly what it was? Do I need to replace the whole motherboard or possibly just some components? I have this computer for 3 years, how much will the repair cost run in case like this?

Thanks!