If you have an analog meter you will see the needle sweep up and down (something that digital units are just not good at doing). Also, is the voltage dropping (hence the beeping) and then rising again. If not, can you take "live" measurements of the 5 volt rail and see what the readings are. If the PS fails to power the computer, and you think it is the 5 volt line, 4.8 shouldn't make any difference to the MB.Originally Posted by greenman100
Also, make sure that you are not exceeding the amperage rating of the 5 volt rail. Drawing too many amps from a PS WILL cause the voltage to drop. If your fluke measure amperage in the 5 to 10 amp range, try and measure to see if there is an amperage spike.