i have no power and when ya turn the puter off it makes a eeeeeeee noise - when one of these goes bad does it take out anything else like the mobo or memory -- how can i test the power supply ? thanks

"makes a eeeeeeee noise " likely the fan for the PSU or CPU. If it is the CPU fan , it might cause the motherboard to shut down immediately and easy to fix. When the PSU goes out it might be the only problem or could take all with it. That includes the key board and monitor. Trying to replace one item at a time does not work to good as the bad component can cause the new to go bad. I would take it to a small comp repair shop. Two e machines of my friend both the PSU and motherboard were bad, CPU and memory were good. There are power supply testers , just google.

emachines desktop computers are well known to have el-cheapo power supplies that tend to fail more often than average.......... See response 2 in this for more details: http://www.computing.net/answers/ha...