I recently replaced my motherboard, cpu, and ram in my desktop and it works fine. I had a spare power supply (about 1 year and 6 months old, NEVER used, it came with my case) so I decided to take my old hardware and build spare pc. I got everything hooked up and when it came time to power it up nothing happened. I noticed that everytime I plug in my power cable, I can hear a very faint "whistle" noise coming from the pc. I cant pinpoint exactly where its coming from because it is so faint. At that point I plugged in a known working power supply and it does the exact same thing. I've done everything I can think of and still now luck. Anyone have any ideas?

Thanks in advance

is it shorting?

make sure the standoffs are in

I did miss one, and I had to reseat the motherboard to get them all in but its still doing the same thing.

open computer case .lay it flat on its side ,turn it on, hover you head all around listing with you best ear into the open case ,and you should be able to pinpoint the whistle

I got it running. As jbennet said, it was shorting.
Thanks

you might of damaged it by shorting it, run diagnostics to check