computer makes a squeeling noise then shuts down
hi iam building a computer out of old bits. i have an asus sk8v mobo 500w psu 4g ram several opteron chips that i can use. i put it all together and got a few error messages which i expected. i swapped the hard drive for another then switched it on and a sqeeling noise came from inside the case and then it shut off. i have bench tested it and even with just the psu plugged in nothing else its still squeels then shuts down. if i remove the 4 pin psu plug from the mobo i dont get a squeel. what do you think could be wrong. could it be mobo, cpu/heatsink, over heating or something else.
thank you in advance.